This is a randomized, double blind, placebo parallel-controlled, multi-center clinical trial. Patients with psoriasis vulgaris were randomly divided into the experiment group （treated with TGP combined with acitretin capsules) and control group （treated with placebo combined with acitretin capsules）.The treatment lasted 12 weeks. The efficacy and safety were evaluated at the baseline, as well as 2, 4, 8 and 12 weeks after the beginning of treatment.The investigator's hypothesis TGP combined with Acitretin Capsulesin is more safe and effective than Acitretin Capsulesin to treat Psoriasis Vulgaris.

Inclusion Criteria:Meet the following conditions

1. Diagnosed according to Classification criteria for Psoriasis vulgaris;
2. Patients aged 18 to 65 years (to the date of screening);
3. PASI grade>7point<20 point;
4. Not treatment in the Topical corticosteroids、Immunosuppresso、Biologicals agents or Tretinoin cream、Phototherapy nearly one months before enrolled.
5. Understanding the whole process of the study, voluntary participation and signed the informed consent;
6. Patient compliance is good, can guarantee in course of observation.

Exclusion Criteria:One of the following is not included in this study:

1. Pregnant women, ready to pregnant or lactating women;
2. Known to root of herbaceous peony total glycosides (TGP) drug allergy;
3. Have a serious heart, lung, kidney and other vital organs and endocrine system lesions and the history
4. Patients is liver function abnormal persons (ALT above the center laboratory normal limit) or hepatitis b patient grain carriers;
5. Need insulin control of diabetes; High blood pressure did not get good controller ;
6. Patients with white blood cells <4.0 × 109 / L, or a definite anemia (hemoglobin less than 100g / L), or platelets <100 × 109 / L, or other blood disease;
7. Patients with chronic diarrhea, or peptic ulcer nearly 1 year;
8. Patients suffering from malignant tumor;
9. Patients suffering from acute and chronic infectious diseases;
10. Mental disorders, history of alcohol abuse, drug or other substance abuse; 11. Other cases which researchers believe that can not enroll.