Objective To evaluate the correlation between PCDH9 and the cell cycle regulation protein(CyclinD1 and C-myc) and explore the role of PCDH9 in regulating cell cycle and promoting tumor progression in the prostate cancer tissues. Methods 92 cases prostate cancer and 36 cases benign prostate samples were collected. PCDH9, CyclinD1 and C-myc protein were detected by immunohistochemical method. Results The positive rate of PCDH9 in prostate cancer tissues (72.8%) was significantly lower than that in benign prostate tissues (100%). The positive expression rates of CyclinD1 and C-myc in prostate cancer tissues were 68.5% and 64.1%, which were significantly higher than those in benign prostate tissues. The positive rates of PCDH9 in prostate cancer patients with different WHO/ISUP classification, PSA level, different clinical stages were statistically significant (P＜0.05). The positive rates of PCDH9 in prostate cancer patients with Gleason score increased, PSA＞20 ng/mL and high clinical stage (Ⅲ + Ⅳ) decreased significantly. The expression of PCDH9 was negatively correlated with the expression of CyclinD1 and C-myc in prostate cancer tissues (r=0.414 and 0.457, P＜0.01). Conclusion PCDH9 is low expression in prostate cancer tissues, and negatively correlated with the expression of cell cycle regulation genes CyclinD1 and C-myc. PCDH9 may promote tumor progression and metastasis by regulating cell cycle protein.