The presetting accuracy of seeker is an important factor for guidance handover in midcourse guidance combined with terminal guidance. Thus, based on the analysis of main guidance handover errors, a correction coefficient method is proposed in analysing the seeker's presetting accuracy due to the radar measurement errors. Integrated with the real target movement locus, the presetting parameters and errors of azimuth and elevation due to the command guidance radar measurement errors are computed. The simulation results indicate that the correction coefficient method can be used to exactly analyse the effects of different parameters on handover and it is an efficient way to research the seeker's presetting accuracy problem.