Objective To evaluate the curative effect and safety of dibutyl phthalate on demodicidosis. Methods A single blinded and controlled study of human demodicidosis treated with dibutyl phthalate was conducted. One hundred and forty three patients with demodicidosis, including 81 acne and 62 rosacea, randomly divided into trial and control groups. The trial group was treated with dibutyl phthalate and control group with "new fumanling" cream twice a day in the early morning and evening respectively for six weeks consecutively. Results The rates of excellent, good, and fair efficacy and total effective rate in the trial group with acne were 53\^7%, 41\^5%, 4\^9% and 100% respectively, with a significant difference to the control group (P0\^05). No complaint of side effects in the trial group was recorded. Conclusion Dibutyl phthalate is highly effective to demodicidosis without prominent adverse reactions.