Prostate cancer is the most common malignancy in the urinary system of males. The remarkable biological and clinical heterogeneity of prostate cancer poses challenges to the initial diagnosis, differential diagnosis, treatment, and prognosis of the disease. Positron emission tomography/computed tomography (PET/CT) is an ideal imaging tool for noninvasive interrogation of underlying tumor biology. Recently, there are a variety of molecular imaging paths and radiopharmaceuticals for the diagnosis and treatment of prostate cancer. This article reviews the current state and prospects of the application of PET in the diagnosis of prostate cancer.