Abstract: Objective To observe the therapeutic effect of traditional Chinese medicine decoction Huoxuexiaozhi capsule on Fatty liver diseases superoxide dismutase (SOD), malondialdehyde (MDA), Cytochrome P450 (CYP450) in blood serum, and approach its mechanism. Methods A prospective randomized controlled study was conducted, including 100 patients who were definitely diagnosed as fatty liver and admitted into affiliated Qinghai University Hospital from January 2014 to December 2016, and they were divided into a treatment group and a control group, 50 cases in each group by random number table method. Traditional Chinese medicine Huoxuexiaozhi capsule was taken orally in treatment group, 4 capsules each time, three times each day, and Dongbaogantai tablet was taken orally in control group, 3 Tablets each time, three times each day. One course of treatment was five weeks.After treatment, the clinic effect was analysed.the changes of patients symptoms, liver function, SOD, MDA, CYP450 in blood serum were studied and analysed. Results Fourteen cases were cured, 18 cases were significantly effective, 12 cases improved and 6 cases were null and void in treatment group, the totol effective rate is 88.0%. Seven cases were cured, 11 cases were significantly effective, 18 cases improved and 14 cases were nulland void in treatment group, the totol effective rate is 72.0%. And there were statistical significant between two groups (P<0.01). Huoxuexiaozhi capsule improved symptoms significantly of fatty liver diseases, such as loss of appetite, often loose stools weak, abdominal distension full side rib pain, nausea and vomiting, there were statistical significant between two groups (all P<0.05). Huoxuexiaozhi capsule improved ALT, AST, γ-GT and ALP, there were statistical significant between two groups (all P<0.01). Huoxuexiaozhi capsule increased SOD, redused MDA and CYP450, there were statistical significant between two groups after treatment (all P<0.01). Conclusion Huoxuexiaozhi capsule can treat fatty liver disease, improve symptoms, liver function, increase SOD, decrease MDA and CYP450, its effect is better than Dongbaogantai tablet (all P<0.01).