The invention discloses a reagent and a method for predicting susceptibility to prostate cancer, belonging to the field of biotechnology. The reagent and the method can be used for predicting susceptibility of a subject to prostate cancer by extracting the genomic deoxyribonucleic acid (DNA) of host cells and testing the genotype of the rs6901250 site on the sixth exon of GPRC 6A gene of the subject; when the genotype of the rs6901250 on the sixth exon of the GPRC 6A gene is AA, the susceptibility of the subject to prostate cancer is the highest; and when the genotype of the rs6901250 is AG or GG, the susceptibility of the subject to prostate cancer is lower. The reagent and the method have the advantages that the correlation between rs6901250 gene polymorphic site and prostate cancer is expounded for the first time; the method for predicting the susceptibility to prostate cancer is provided; and the method can be used for early prevention diagnosis and auxiliary diagnosis of prostate cancer, and is also used for research and development of new medicines.