Objective To study the collelation between the 18F-FDG (FDG) PETCT (positron emission tomography) maximum standardized uptake value (SUVmax) and PSA (prostate specific antigen) in the diagnosis and treatment of prostate cancer. Methods A total of 37 cases which diagnosed of prostate cancer were selected as the observation group, and 28 cases of benign prostatic hyperplasia patients as a control group. Two groups of patients underwent PSA screening and 18F-FDG PETCT inspection. In SUVmax> 2.5, free PSA / total PSA (f/t) <0.16 as the standard diagnosis of prostate cancer. Researchers two groups of patients by 18F-FDG PETCT generated image of radioactivity distribution of positive lesions ROI measurement, calculation SUVmax. Statistical analysis SUVmax correlation with PSA. Results 37 cases tPSA 4-10ng/mL in 28 cases, tPSA> 10ng / mL in 9 cases, control group of 28 patients, tPSA 4-10ng/mL in 17 cases, tPSA <4ng/ mL in 11 cases. Observer Group f/t significantly lower than the control group. SUAmax observation group was significantly higher. After correlation analysis, SUVmax and fPSA positive correlation (t=0.877, P<0.05). SUVmax with f/t negative correlation (t=0.988, P <0.05). Conclusion SUVmax positively correlated with fPSA, SUVmax with f/t negative correlation for patients with prostate disease in diagnostic gray zone, SUVmax combined with f/t can significantly improve the accuracy of diagnosis of prostate cancer.