The separation system is crucial for the launch of satellites. Dynamic characteristics of satellite separation are quite complex and difficult to predict. With respect to the helical compression spring mechanism, an approach using transient perturbation analysis is presented. The separation springs and limit switches are mathematically modeled, and disturbing forces and moments are considered. ADAMS and MATLAB software platforms are combined to obtain separation trajectory and attitude parameters. The minimum relative distance is proposed to show whether there is collision between the satellite and launch vehicles. Emphasis is placed on introducing the approach by analyzing a typical separation system. With experimental design and statistical analysis, the influences of perturbation factors are concluded. For example, three angular velocities are approximately linear with center of gravity offsets of the satellite and deviations of spring parameters; however, the effect law of asynchronous time is non-linear. A ground test system of satellite separation is designed and the test results are compared with the analysis, which prove accuracy of the dynamic model and feasibility of the approach.