Objective To observe the clinical efficacy of combined therapy of Sanyu Xiaoyin Decoction（ 散瘀消银汤） in the treatment of severe plaque psoriasis. Methods Totally 90 cases of severe plaque psoriasis treated in our department from April 2013 to December 2016 were randomly divided into 45 cases respectively in the treatment group and the control group. The control group was treated with traditional Chinese medicine bath combined with NBUVB irradiation

coated with Calcipotriol Ointment; Treatment group was added Sanyu Xiaoyin Decoction. The changes of PASI during the treatment were observed and 4 weeks were 1 courses. A total of 3 courses were observed

and the recurrence was followed up after half a year. Results The total effective rate of the treatment group was93. 3%

and the total effective rate of the control group was 75. 6%. The treatment group was better than the control group（ P < 0. 05）. After 2 courses and 3 courses of treatment

PASI score of the treatment group was significantly lower than the control group（ P < 0. 05）. Compared with before treatment

after 2 courses of treatment

the score of PASI in both the treatment group and the control group was lower than that before the treatment（ P < 0. 05）. After 3 courses of treatment

the scores of PASI in both the treatment group and the control group were all lower than that of the 2 courses（ P < 0. 05）. There was no obvious adverse reaction in the treatment group

and the control group showed the symptoms of erythema and pruritus

and decreased gradually after reducing the dose of NB-UVB irradiation. Conclusion The combined therapy of Sanyu Xiaoyin Decoction is effective and safe in the treatment of severe plaque psoriasis

with low relapse rate. It is worthy of popularization and application.