Hexaphenyl cyclotrisilazane was synthesized from diphenyl dichlorosilane and ammonia with toluene as solvent.The effects of input material concentration, reaction temperature, ammonia flow rate and separation method on product yield were investigated.The structure of hexaphenyl cyclotrisilazane was characterized with FTIR and XRD.It was found that when diphenyl dichlorosilane concentration was 0.96 mol·L -1 , reaction temperature was 111—112℃,NH_3 flow rate was 0.02 m3·h -1 , the yield of hexaphenyl cyclotr...