Objective To study the effect of camphor oil in killing Demodex in vitro and to further analyze the killing mechanism.Methods The mites were collected with adhesive cellophane tape and randomly divided into six groups.The killing effect of camphor oil was investigated with different concentrations against Demodex in vitro.The reaction progress was pictured using Motic Images software.Results Camphor oil had better killing effect on Demodex folliculorum than on D.brevis in vitro.The death rate increased with the drug concentration and time.The most suitable and effective concentration of killing both Demodex folliculorum and D.brevis in vitro was 12.5%.After the drug was given,the mites contracted and twisted,and then relaxed and died.Conclusion Camphor oil has strong killing effect on Demodex in vitro.The main mechanism of camphor oil may be related to direct contact and neuromuscular toxicity.