Solvent-extraction method is often used to separate organic compounds. The reaction compounds are separated by means of solvent-extraction with phosphoric acid and aminie salt as extracting (agents) in this work. The influence of technology condition on separation process is discussed. It is showed that the mass fraction of dimethyl-thioltoluenediamine(DMTDA) increases from 0.814 to 0.949, and the percent recovery of DMTDA reaches 95.1% after single-stage extraction. The optimized mixing time is 15 minute; volumn ratio of extracting agent to material liquid is 2, and the proper concentration of extracting agent is 2.5% under the normal temperature.