To evaluate the clinical efficacy and safety of indigo naturalis ointment in treating psoriasis in the active stage of the blood-heat syndrome.Methods:A total of 80 patients with psoriasis(blood-heat syndrome) in the active stage were selected.According to the random number table，the patients were divided into the treatment group(40 cases) and the control group(38 cases).All patients were orally treated with Bailing Xiaoyin Granules.The treatment group was topically treated with indigo naturalis ointment twice a day，and the control group was topically treated with calcipotriol ointment twice a day.The course of the treatment was eight weeks.The objective skin lesion symptom，namely psoriasis lesion area and severity index(PASI) score was observed，and the visual analogue scale(VAS) score of subjective itching symptom was calculated.Adverse reactions of these patients were recorded.Results:The total effective rate for the PASI score of objective skin lesion symptom was 85% in the treatment group，which was significantly higher than that of the control group(73.68%)，and the difference(P<0.05) was statistically significant.As for subjective itching symptoms，the effective rate in the treatment group was 90%，which was higher than that of the control group(71.05%)，and the difference(P<0.05) was statistically significant.In terms of security，two patients in the control group had different degrees of irritation.After emollients were applied topically，local symptoms were relieved.All 40 patients in the treatment group completed the observation without any adverse reactions.Conclusion:Indigo naturalis ointment can effectively improve the objective skin lesion symptom and subjective itching symptom of patients with psoriasis in the active stage of blood-heat syndrome，with fewer adverse reactions.