In the conventional servo system, model analysis according to motor axis and base space is used as a reference. However, when analyzing the stabilized platform, it is not compatible due to in which exists inertial space and base space. In order to solve this problem, the multiple reference frame model was proposed, where direct-current motor model was based on inertial space. On the basis of the multiple reference frame model, an improved Particle Swarm Optimization(PSO) algorithm was also proposed. As a kind of swarm intelligence algorithm, PSO was widely used in parameters optimization. The traditional PSO on inertial weight and slopping-over borders were improved, and then, it was adopted in tuning and optimization of PID parameters. The simulation and experiments results indicate that the improved PSO(IPSO) PID controller can obviously enhance the static precision and effectively isolate the vibration and disturbance of carrier.