The stability precision is the key technical factor of optical-electro inertially stabilized platform. Combined with the mechanism of inertially stabilized platform system, the mathematical model of the pitch gimbal of inertially stabilized platform is established. The disturbance impacts of stability precision are analyzed and concluded in this paper. And the expression about how the disturbance source impact line of sight precision are deduced by the analysis of mathematical mode with classical engineering control algorithm. The analyses are validated by simulations and experiments, which may provide the reference for engineering application. © 2017 IEEE.