Serious geometric distortion in IR linear scanning image will affect the tactical efficiency of patrol missiles, which is generated from high speed maneuvering, large filed of view(LFOV), pendulum scanning of the missile-borne image. The strict imaging model was constructed by converting the pixel serial numbers of infrared image into certain map projection coordinates of the surfacial scene, which was composed of four equations. Image plane coordinates equation was built by pixel parameters of infrared chip surface. Image spacial coordinates equation was built to transform image plane coordinates into earth-centered earth-fixed(ECEF) coordinates. The surfacial object coordinates equation was built in ECEF system by collinear equation and the earth surface model. The last map coordinates equation was built by certain map projection model form the object ECEF coordinates. The static simulation of geometric distortion was implemented in Matlab to ascertain the effect of model parameters such as navigation height, pendulum angle, the earth model and so on. The results could be used as the basis for the engeering optimization of geometric distortion cerrection algorithm.