Objective:To observe the preventive effects of Tongyu Decoction on cardiovascular events after castration of prostate cancer. Methods110 patients with prostate cancer were randomly divided into the treatment group and control group, 55 cases in each group. The control group was treated with castration therapy, and the treatment group was treated with Tongyu Decoction based on the treatment for the control group, with a treatment course of 3 months and follow-up of 6 months. The occurrences of cardiovascular events and end events were observed. The changes of cardiovascular events related indicators including fasting insulin (FINS), fasting blood glucose (FBG), carotid artery intima-media thickness (IMT) and high sensitivity C-reactive protein (hs-CRP) were compared.  Results:①During the research, the cardiovascular events occurred in 14 patients in the control group, including 1 case of cerebral infarction, 2 cases of cerebral hemorrhage, 9 cases of intracranial lacunar lesions, 1 case of myocardial infarction and 1 case of angina (among 1 case of cerebral hemorrhage and 1 case of myocardial infarction were dead), the incidence rate was 25.45%. The cardiovascular events occurred in 4 patients in the treatment group, all of them were observed intracranial lacunar lesions and no one died, the incidence rate was 7.27%. There was statistically significant difference on the incidence rate of cardiovascular events between the two groups, and the incidence rate in the treatment group was obviously lower than that in the control group (P<0.05). ②Compared with treatment before, the levels of IMT, hs-CRP and IRI were decreased in the treatment group after treatment, with statistically significant differences (P<0.05), while the levels of IMT and hs-CRP were increased in the control group after treatment, with statistically significant differences. After treatment, there were statistically significant differences on the levels of IMT, hs-CRP and IRI between the two groups, and the improvement on these indicators in the treatment group was better than that in the control group (P<0.05).  Conclusion:Tongyu Decoction can significantly reduce the incidence of cardiovascular events after castration of prostate cancer, and play the synergistic effects with castration therapy for prostate cancer. Its mechanism may be related to decreasing insulin resistance and inhibiting hs-CRP.