Psoriasis is a common and chronic disease in dermatological clinical settings. Dermatologists often estimate the impact of the disease to patients by their intuition. Accurate measurement of psoriasis disability is essential for the development of treatment strategy and evaluation of its efficacy. This paper describes several measures of psoriasis severity which involve the rating of symptom ��such as psoriasis area and severity index ��PASI��, psoriasis global assessment ��PGA�� and lattice system physician's global assessment (LS-PGA)) and health-associated life quality (including general health questionnaires, dermatology specific questionnaires, disease specific questionnaires), as well as the criteria for definition of severe psoriasis. to the primary health staffs or health administrative departments. New methods have provided potency therapies to psoriasis patient as some new biological medicines go on the market continuously in recent years. In order to decrease the potential risks and side effects of applying in clinic, it is very necessary to assess the severe degree of the psoriasis patient correctly for making a strict and reasonable applying index. We have reviewed the research progress of measurements of disability of psoriasis patients and judgment standards as possible.