Double-station IR ranging system on mobile platform has higher practicability. By analyzing the process of ranging, the principle of coordinate transformation and the conception of space crossing are described. And the method of double-station IR ranging on mobile platform is introduced. Incorporating with the requirements of practical application, the elements influencing the ranging accuracy of the ranging algorithm are analyzed. And error expressions are given. Simulation analysis for ranging accuracy is performed and the relationships of double-station distance, detected azimuth and ranging accuracy are researched.