Abstract: Objective To understand the etiology and epidemiology of a dermatitis outbreak in a primary school in Shenzhen, Guangdong province and provide evidence for the prevention and control of dermatitis. Methods Case-control study was conducted to analyze the risk factors; Moth larvae were captured for etiological identification. Results Eighty nine cases were surveyed and maculopapule on exposed skin was the major clinical symptom. The attack rate was 32.79%, in males (60/183) and 27.62% in females (29/105), the difference had no statistic significance (2=0.83, P 0.05). The captured larvae were identified as Euproctis plana. The case-control study indicated that frequent stay under the trees with the larvae (OR=5.88, 95% CI:2.73-12.69), direct contact with larvae in school (OR=3.31, 95% CI:1.57-7.01) and inappropriate clothes protection (OR=2.36, 95% CI:1.07-5.22) were the risk factors. Conclusion A caterpillar dermatitis outbreak caused by Euproctis plana larva was identified for the first time. Exposure to this kind of caterpillar or related fomites such as setae could cause typical sensitization dermatitis. It is suggested to conduct prevention for the health of students and the public.