Evaluate the efficacy and safety of Calcipotriol Betamethasone Ointment and Calcipotriol Ointment in sequential therapy

1.240 subjects will be randomized 1:1:1 divided into the 3 groups 2.Week0 to Week4,each group were treated with Calcipotriol Betamethasone Ointment 3.Week4 to Week12, the there group were respectively treated with Calcipotriol Betamethasone Ointment,Calcipotriol Ointment and Urea Cream 4.The efficacy and safety were evaluated at the baseline, as well as 1, 4, 8 and 12 weeks after the beginning of treatment.

Inclusion Criteria:

1. Subjects who signed Informed Consent Form；
2. Male or female subjects 18-65 years of age；
3. Clinically confirmed diagnosis of plaque psoriasis as per the diagnostic criteria for psoriasis vulgaris specified in Clinical Dermatology.
4. Involved area 1-10% of the body surface area.

Exclusion Criteria:

1. Incompliance with the diagnosis of plaque psoriasis or plaque area > 10% of the body surface area.
2. Erythrodermic psoriasis, psoriasis arfhropathica or pustular psoriasis;
3. Known allergy to any component of the test or control drug；
4. Concomitant allergic skin disease such as eczema， contact dermatitis and urticaria, or other serious and/or extensive skin disease；
5. Systemic medication or ultraviolet therapy for psoriasis within 4 weeks prior to study initiation；
6. Topical use of external drug for psoriasis within 2 weeks prior to study initiation；
7. Women of child-bearing potential who are pregnant, plan to become pregnant during study or are lactating；
8. Glucocorticoid or immunodepressant, or hypoleukemia due to tumor or chemotherapy within the last 4 weeks；
9. Serious life-threatening condition that allows a life expectancy of less than 2 months；
10. Inability to guarantee taking medications and completing visits as scheduled during the study;
11. Serious infection that is not suitable for external treatment；
12. Any other condition that the investigator deems unsuitable for entering the study.