Abstract: The impact attenuation technology is more and more widelyused in recovery system of spacecraft.The two kinds of retrorocketthrust mode applied in impact attenuation process are compared in thispaper,and the factors are analysed which influence the final perfor-mances of the system in impact attenuating process.The changes of systeminitial and environment conditions are regarded as the maximum inf-luence factor,so a pragmatic control method is put forward to solve thisproblem.By applying this method the influence of the changes of theinitial and environment conditions on the performances of impact attenu-ation device can be eliminated ultimately.