clinical demonstration research of

INTERVENTION: A:PSORI‐CMO1 decoction plus Calcipotriol Betamethasone Ointment ;B:Placebo decoction plus Betamethasone Ointment ; CONDITION: psoriasis vulgaris PRIMARY OUTCOME: relapse rate of Psoriasis vulgaris during the treatment period;PAS; SECONDARY OUTCOME: time interval until relapse;onset time;the dosage of external use for western medicine;VAS;DLQ; INCLUSION CRITERIA: 1. Male and female aged 18 to 70 years old; 2. Patients with a PASI index more than 7 and less than or equal to 20, and BSA less than 30%; 3. signed written informed consent.