Objectives: To study symptom differentiation for yang deficiency and blood heat based on 117 psoriasis patients. Methods: Obtained frequency analysis (%), mean (%), and OR, CL(P-value) with prospective pre-post intervention design and multiple regression analysis. Results: There were no statistically significant differences as to sex, BMI, smoking and marital status, but there were statistically significant differences in variables of average age, family history, and alcohol consumption (P<0.05). There were no statistically significant differences in psoriasis symptoms as to initial age of onset, morbidity span, area of the initial onset, and the progression of psoriasis during the last three months of each patient. However, the type of psoriasis showed a statistically significant difference (p=0.011). While there were no statistically significant differences as to common cold, condition of psoriasis after recovering from the cold, skin condition, exercise, and seasonality, irregular perspiration showed significant difference (p<0.00). When confounding factors have been controlled the blood heat patient group as the comparison group, multiple regression analysis showed OR, CI(95%) of 1.06(0.31-3.63) for men, 0.28(0.08-1.06) for aged 30 to 49,0 and 0.18(0.04-0.80) for aged 50 and older. it was 0.06(0.01-0.7) for family history, 1.06(0.29-3.88) for drink alcohol, 19.90(2.53-156.7) for seasonality, and 10.28 (3.19-33.11) for perspiration problems. In these variables, Sex, age, smoking, and alcohol consumption showed no statistically significant results, but family history(p=0.049), seasonality(p=0.005), and irregular perspiration (p=0.017) were statistically significant. Conclusion: Family history, seasonality and irregular perspiration are the determining factors for yang deficiency and blood heat in psoriasis.