RNA modification is an important part of epigenetic regulation. However, the relationship between RNA modification writers and prostate cancer (PCa) remains unclear. We obtained transcriptome data from The Cancer Genome Atlas; the expression of writers for four RNA modifications (N6-methyladenosine, N1-methyladenosine, alternative polyadenylation and adenosine-to-inosine RNA editing) was altered in PCa tissue when compared with normal tissue. RNA modification writers affect the expression of immune checkpoints. Gene ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the RNA modification was related to the cell cycle. Hub genes were screened using machine learning, and a risk score model was established using multivariate Cox analysis. Univariate and multivariate Cox analyses showed that a risk score model based on RNA modification writers could be an independent prognostic factor for PCa. In conclusion, our study showed that RNA modification writers are differentially expressed in PCa and might influence the development of PCa by regulating immune checkpoints and the cell cycle. The risk score model of RNA modification writers is predicted to be an independent prognostic factor for PCa. Thus, RNA modification writers might be used as potential indicators for the clinical diagnosis of PCa.