Objective:To explore clinical effect of 125I radioactive seed implantation combined with intermittent hormonal therapy (IHT) on prostate cancer. Methods:During the period from May 2016 to May 2017, 84 patients pathologically diagnosed with prostate cancer of T 3N 0M 0 by biopsy in Affiliated Hospital of Chifeng College were enrolled as study objects. They were divided into two groups by random number table method. 40 cases in control group were treated with intermittent hormonal therapy, while 44 cases in observation group were treated with 125I radioactive seed implantation combined with IHT. After the first IHT, time of prostate specific antigen (PSA) returning to normal and intermission time in both groups were observed. The dynamic changes of PSA level and prognosis in both groups during treatment were recorded. Results:After the first IHT, time of PSA returning to normal in observation group was shorter than that in control group, while intermission time was longer than that in control group ( P<0.05). At 3, 6, 12 and 24 months after treatment, PSA level in observation group was lower than that in control group ( P<0.05). The 2-year PSA-free progression survival (PSA-PFS) rate in observation group was higher than those in control group (77.27% vs 45.0%) ( P<0.05). There was no significant difference in 2-year total overall survival (OS) rate between the two groups ( P>0.05). There were no serious complications during treatment in observation group. Conclusions:125I radioactive seed implantation combined with IHT in treatment of prostate cancer can reduce PSA level more quickly, and increase 2-year PSA-PFS rate.