A survey indicated that the prevalence of Demodex infection among 512 college students in Tangshan was 36.3% (186/512), that of males and females was 39.3% (81/206) and 34.3% (105/306) respectively (P>0.05). The infection of Demodex folliculorum accounted for 82.3% (153/186), followed by D. brevis (7.5%, 14/186) and mixed infection (10.2%, 19/186). The prevalence was 47.0% (93/198) in subjects with oily skin, 26.6% (37/139) in those with dry skin, and 33.9% (56/165) in mixed-type skin (P<0.05). Subjects with facial diseases (62.0%, 75/121), such as rosacea and acne, were more likely to be infected with Demodex than those with healthy skin (27.6%, 80/290) (P<0.05). Prevalence in those lived in humid environment (67.9%, 95/140) was higher than those lived in the desiccating environment (24.5%, 91/372) (P<0.05).