Abstract: At present, the piggyback is often applied to small satellites launching, while the research of launching sub-satellites from secondary payload adapter of primary satellite is undeveloped. In this article, Adams simulation was made about the separation process of secondary separation structures. Firstly, the rational parameters were selected on the basis of the simplified model. After that, the simulation analysis and dynamic calculating were carried out and the velocity and angle velocity of one sub-satellite' separation were obtained. Finally, it could be concluded that the Adams model was correct comparing results. The conclusion of this article is of great importance on the design and the research of new small satellites.