Abstract: Pre-processing of data is one of the essential works for Doppler satellite positioning.In this paper,in which the MIV data are regarded as an object of study,the followings mathematical methods,of pre-processing are dealt with,namely the decoding of the satellite messages,the fitting of the satellite orbit,the calculation of the satellite coordinates and elevation,the distance between the satellite and station,and the correction of the Doppler counts,etc.Also,some important formulas and criterions of the error limits are derived or proved with simple methods and some new conceptions such as the determination of direction of the satellite motion are discussed.