Using 3-chloropropyl triethoxysilane and sodium hydrosulfide aqueous solution as raw materials，the 3-mercaptopropyl triethoxysilane（silane coupling agent KH580） was prepared by direct heating condensation with suitable catalyst，and the effects of reaction temperature，reaction time and catalyst dosages on the purity and yield of silane coupling agent KH580 were studied.The results showed that with the increase of reaction temperature，the prolongation of reaction time and the increase of catalyst dosages，the yield and purity of silane coupling agent KH580 increased，and the increase tended to be flat as the reaction conditions reached a certain value.Finally，the optimal synthesis process for silane coupling agent KH580 was determined to be：reaction temperature 65～70 ℃，reaction time 4 h，catalyst dosage 6%.
