The invention discloses a purification method for TCPP (trichloropropylphosphate), wherein phosphorus oxychloride and propylene epoxide are taken as raw materials for reaction so as to produce TCPP, before reaction, water with 0.01 to 0.06 percent of phosphorus oxychloride in mass and TCPP with 2 to 12 percent of phosphorus oxychloride in mass are added, and then propylene oxide is dripped into an reactor until the reaction is finished. The method provided by the invention is simple, and effectively overcomes the defects of high chromaticity and odor in TCPP, and meanwhile, the method can not cause any pollution, and is suitable for application and use.