Abstract: Hexaphenyl cyclotrisilazane was synthesized from diphenyl dichlorosilane and ammonia with toluene as solventThe effects of input material concentration, reaction temperature, ammonia flow rate and separation method on product yield were investigatedThe structure of hexaphenyl cyclotrisilazane was characterized with FTIR and XRDIt was found that when diphenyl dichlorosilane concentration was 096 mol·L-1, reaction temperature was 111—112℃,NH3 flow rate was 002 m3·h-1, the yield of hexaphenyl cyclotrisilazane could reach 911%Using ammonia water was better than hot filtration to weed out ammonium chloride at the period of product separationIt enhanced separation efficiency and simplified the processAt the same time it also decreased pollution to the environment by reducing volatile matter of toluene.