A method for the preparation of Prodiamine. It includes the following steps: 1) adding 2,4-dichloro-3,5-dinitrobenzotrifluoride and water in a reactor, adding di-n-propylamine and an inorganic base dropwise under heating and stirring, holding the reaction at 80~90C for 1~2 hours after dropping and cooling, to obtain N,N-dinitropropropylamine-3-chloro-2,6-dinitro-4-trifluoroaniline; 2) adding solvent with the weight ratio of 0.5:1~10:1 N,N-di-n-propylamine-3-chloro-2,6-dinitro-4-trifluoroaniline, pass ammonia for diamination reaction for 1~2 hours, diamination reaction temperature is 70~140 , cooling, filtration, washing, drying, to get the product Prodiamine.
