The present invention relates to a compound essential oil for treating psoriasis, comprising carrier oil, cedar essential oil, thyme essential oil, lemongrass essential oil, cinnamon essential oil, and geranium essential oil. The volume parts of each ingredient are as follows: cedar essential oil 1-5 parts thyme essential oil 1-5 parts lemongrass essential oil 2-8 parts carrier oil 100 parts, wherein the total parts of cedar essential oil, thyme essential oil, and lemongrass essential oil are 10 parts. The compound essential oil for treating psoriasis also comprises 10 parts of cinnamon essential oil or geranium essential oil, or a mixture at any ratio of these two. This invention produces a compound essential oil for treating psoriasis through a proper proportioning, using the effectiveness and synergistic effect of each ingredient to perform treatment of the affected area physiologically while using the mental efficacy of each ingredient to soothe mood of patient, resist depression, and boost spirit psychologically.一種治療牛皮癬用複方精油,包括基底油以及雪松精油、麝香草精油、檸檬草精油、肉桂精油以及天竺葵精油,各成分的體積份數如下:雪松精油1-5份,麝香草精油1-5份,檸檬草精油2-8份,基底油100份,其中雪松精油、麝香草精油和檸檬草精油的總份數為10份。該治療牛皮癬用複方精油還包括肉桂精油或天竺葵精油或兩者按任意比的混合物10份。本發明通過合理的配比,製得適用於治療牛皮癬的複方精油,在利用各成分的功效和協同作用,從生理上對患處進行治療,同時利用各成分的精神功效,從心理上舒緩患者情緒、抗壓抑、提振精神。