Abstract: Hoisting is one of the most important processes in assembly of spacecraft. Hydraulic positioner is able to control the assembly procession of spacecraft. Because the size of China′s spacecraft gets larger，and the weight gets heavier，the requirements of stability and safety in hoisting process are becoming more strict. Basing on the assembly process of spacecraft，this paper put forward a calculation model of impact acceleration for spacecraft assembly. One spacecraft is taken for example，which simulation model is built. The drop impacts of spacecraft from different heights are simulated by ADAMS software. The accelerating curve of the drop impacts is achieved，which shows that higher precision of height controlling in hoisting is better for the safety of spacecraft. The result of this paper has practical value for spacecraft hoisting.

Key words: spacecraft, hoisting, hydraulic positioner, collision analysis, ADAMS