Abstract: Objective To explore the immune function of prostate cancer patients and its relationship with clinicopathological features of prostate cancer. Methods Total 60 cases of patients with prostate cancer in our hospital from January 2014 to December 2016 were assigned into the prostate cancer group, and 60 healthy subjects into the control group. The levels of CD4⁺, CD8⁺, CD4⁺/CD8⁺ and natural killer cells (NK) were detected by using flow cytometry. Results The levels of CD3⁺, CD4⁺, and CD4⁺/CD8⁺ in prostate cancer group were lower than those in the control group (P<0.05), the levels of CD8⁺ and NK cells were higher than those in the control group (P<0.05). There was no significant difference in the levels of CD3⁺, CD4⁺, CD8⁺, NK and CD4⁺/CD8⁺ between the prostate cancer patients with volume≥60 mL and volume <60 mL (P>0.05). The CD3⁺, CD4⁺ and CD4⁺/CD8⁺ in the medium-poorly differentiated prostate cancer patients were significantly lower than in well differentiated patients (P<0.05), the CD8⁺ and NK cells were higher than those in well differentiated patients (P<0.05). The levels of CD3⁺, CD4⁺ and CD4⁺/CD8⁺ in the stage Ⅰ-Ⅱ prostate cancer patients were lower than those in the stage Ⅰ-Ⅱ patients (P<0.05), the CD8⁺ and NK cells were higher than those in stage Ⅰ-Ⅱ patients (P<0.05). The levels of CD3⁺, CD4⁺ and CD4⁺/CD8⁺ in patients with lymph node metastasis were lower than that in patients without lymph node metastasis (P<0.05), the CD8⁺ and NK cells were higher than those without lymph node metastasis (P<0.05). Conclusion The immune function in prostate cancer patients is low. The low immune function of prostate cancer patients is related to prostate cancer differentiation, clinical stage and lymph node metastasis, and is not related to tumor volume. The lower differentiation, higher clinical stage and lymph node metastasis are closely correlated with the higher degree of immune dysfunction.