In order to analyze the homing precision of the missile which adopts terminal IR imaging guidance, it is necessary to estimate the error of seeker′s output. In this paper,the control system of the stabilized platform of an infrared staring imaging seeker is analyzed firstly. Then,the imaging error and disturbing error from missile, as well as drift error from the main components and coordinate system error in the output of the seeker are studied, and calculating equations for each of them are derived. In addition, based on the analysis above, the practical methods are proposed in order to effectively control the errors of the seeker′s output, and improve its precision.