Objective To observe the curative effect of Di\|n\|butyl phthalate\|OP emulsion in the treatment of demodicidosis. \ Methods\ 447 cases with Demodex infection on face were treated with Di\|n\|butyl phthalate\|OP emulsion. Among them, 30 cases suffering from acne, tetter and pustule were also randomly observed. 20 days after treatment negative conversion rate and the therapeutic effect were evaluated. At the same time, the effect of this solution was compared with that of other three medicaments (FuManLing, 2% metronidazole and 8% metronidazole preparations). In vitro test of mites\|killing, toxicity test in experimental animals and the safety evaluation for local application were also performed. \ Results \ Results showed that the negative conversion rate was 92\^8%(415/447), effective rate for the cases showing evident face damage was 90\^0%(27/30). The result also indicated that the OP emulsion medicament was more effective than other three medicaments (P