Objective To investigate the infection of demodicid mite in medical students. Methods Questionnaires were distributed to understand medical students' cognition of demodicid mite infection, and transparent adhesive paper method was used to sample and detect demodicid mite infection. Results A total of 2380 valid questionnaires were collected. Among them, 66.76% believed that demodicid mite infection was not related to age, and 77.19% believed that they were infected with demodicid mite. Among the 244 students, 89 were positive, and the infection rate was 36.48%. The infection rate of boys was 37.21%, which was not significantly different from that of girls (36.32%) (P >0.05). The infection rate of junior college students was 45.45%, which was higher than 29.10% of secondary school students, and the difference was statistically significant (P <0.05). 535 samples of other parts of the body and personal supplies were randomly sampled, and 12 were positive. Demodex mite was detected in the back, soles of feet, mattresses, pillows and towels. Conclusion The infection rate of demodicid mite is related to the age of the students, and has nothing to do with the students' facial conditions, obesity, exercise habits, cleansing methods and so on.