Abstract: Objective To observe the differences in normal facial skin thickness and echo density by different ages and sites of healthy adults of the same sex using 50 MHz high-frequency ultrasound. Methods From January to June 2019, 200 healthy adult volunteers with normal facial skin who were from Sichuan, Yunnan, Guizhou, and Chongqing and met the inclusion criteria were recruited by the Affiliated Hospital of Southwest Medical University with simple random sampling method, and then were included in this cross-sectional investigation study. Then 50 MHz high-frequency ultrasound was used to obtain skin ultrasonogram of volunteers′ forehead, canthus, eyelid, and cheek. According to the ages, 100 female volunteers were divided into 20-29 years old (30 females), 30-39 years old (25 females), 40-49 years old (20 females), and 50-70 years old (25 females) groups; 100 male volunteers were divided into 20-29 years old (30 males), 30-39 years old (25 males), 40-49 years old (20 males), and 50-70 years old (25 males) groups. The thickness of full-skin, the upper dermal echo density, and the lower dermal echo density of the female and male volunteers′forehead, canthus, eyelid, and cheek were recorded respectively. Data were statistically analyzed with one-way analysis of variance, analysis of variance for repeated measurement, least significant difference test, and Bonferroni correction. Results (1) The thickness of full-thickness skin in forehead, canthus, eyelid, and cheek of female and male volunteers in 20-29 years old group were (1.86±0.26), (1.36±0.11), (1.24±0.25), and (1.90±0.21) mm, (2.45±0.37), (1.64±0.19), (1.44±0.16), and (2.53±0.26) mm, respectively, in 30-39 years old group were (1.98±0.24), (1.43±0.13), (1.15±0.15), and (2.12±0.13) mm, (2.34±0.27), (1.63±0.27), (1.50±0.38), and (2.43±0.40) mm, respectively, in 40-49 years old group were (1.90±0.21), (1.43±0.18), (1.24±0.27), and (1.98±0.12) mm, (2.14±0.24), (1.54±0.25), (1.28±0.14), and (2.39±0.36) mm, respectively, in 50-70 years old group were (1.64±0.25), (1.36±0.19), (1.16±0.12), and (1.89±0.29) mm, (2.28±0.27), (1.73±0.25), (1.58±0.18), and (2.38±0.32) mm, respectively. There were no statistically significant differences between female volunteers in the 4 groups and male volunteers in the 4 groups in thickness of full-thickness skin in canthus, eyelid, and cheek (F=0.677, 0.666, 0.136, 0.697, 0.294, 0.888, P>0.05). The thickness of full-thickness skin in forehead and cheek of the female volunteers in the 4 groups and male volunteers in the 4 groups was similar (P>0.05), and was significantly higher than that of canthus and eyelid (P<0.05). The thickness of full-thickness skin in canthus and eyelid of female volunteers in 20-29 years old, 40-49 years old, and 50-70 years old group was similar (P>0.05), while thickness of full-thickness skin in canthus and eyelid of male volunteers in the 4 groups was similar (P>0.05). (2) The upper dermal echo density of forehead, canthus, eyelid, and cheek of female volunteers in 50-70 years old group was significantly lower than that in 20-29 years old and 30-39 years old groups (P<0.05). The upper dermal echo density of forehead, canthus, eyelid, and cheek of male volunteers in 50-70 years old group was significantly lower than that in 20-29 years old group (P<0.05). The upper dermal echo density of forehead, canthus, eyelid, and cheek of female and male volunteers in 20-29 years old and 30-39 years old groups was similar (P>0.05). The upper dermal echo density of forehead and cheek of female volunteers in 20-29 years old, 40-49 years old, and 50-70 years old groups was significantly lower than that of canthus and eyelid (P<0.05). The echo density of upper dermis of cheek of male volunteers in the 4 groups was significantly lower than that of canthus and eyelid (P<0.05). The upper dermal echo density of canthus and eyelid of female volunteers in the 4 groups and male volunteers in the 4 groups was similar (P>0.05), the upper dermal echo density of forehead and cheek was similar (P>0.05). (3) The lower dermal echo density of forehead, canthus, eyelid, and cheek of female volunteers in 50-70 years old group was significantly higher than that in 20-29 years old and 30-39 years old groups (P<0.05). The lower dermal echo density of forehead, canthus, eyelid, and cheek of male volunteers in 50-70 years old group was significantly higher than that in 20-29 years old group (P<0.05). The echo density of the lower dermis of forehead, eyelid, and cheek of female and male volunteers in 20-29 years old, 30-39 years old, and 40-49 years old groups was similar (P>0.05). The lower dermal echo density of forehead and cheek of female volunteers in the 4 groups was significantly lower than that of canthus and eyelid (P<0.05). The lower dermal echo density of forehead and cheek of male volunteers in 30-39 years old, 40-49 years old, and 50-70 years old groups was significantly lower than that of canthus and eyelid (P<0.05). The lower dermal echo density between canthus and eyelid and between forehead and check of female volunteers in the 4 groups and male volunteers in the 4 groups was similar (P>0.05). Conclusions The 50 MHz high-frequency ultrasonography shows that the thickness of full-thickness skin of canthus, eyelid, and cheek is similar in all age groups of female and male adult volunteers with normal facial skin. In the same age group, the thickness of full-thickness skin of forehead and cheek of male and female volunteers is significantly higher than that of canthus and eyelid. The upper dermal echo density of forehead, canthus, eyelid, and cheek of female and male volunteers shows a decreasing trend with age, while the lower dermal echo density shows an increasing trend with age. In addition, the echo density of upper and lower dermis of canthus and eyelid was significantly higher than that of cheek in all the four age groups.