In order to reduce the satellite launch cost and improve the efficiency ratio of launch vehicles, the stacked launch mode of “one rocket launch multi-satellites” is increasingly used for domestic and foreign space launch missions of microsatellites. In order to explore the collision risk during the separation of multiple satellites, a stacked configuration of one rocket with 18 satellites is established in this paper. Through mathematical derivation and MATLAB simulation, the relative motion trajectories of two satellites in the same layer during separation are established. The result shows that there is no risk of separation collision between two satellites in the same layer. In addition, the paper uses ADAMS to model the stacked satellite cluster, and adopts the Monte Carlo method to obtain the separation simulation results influenced by the random combination of multiple disturbance factors, which is used for statistical modeling. Also, the paper explores the effects of different rotation axis, rotation angular velocity, mass eccentricity of buffering rubber and delay of unlocking device on the separation of the stacked satellite cluster. The conclusion indicates that the buffering rubber should be selected with appropriate stiffness and designed with the same center of mass as the satellite, moreover, the delay of the unlocking device should be as low as possible to reduce the risk of collision when the satellites are unlocked and separated.