Abstract: The stepping of the VISSR of the FY-2A Meteorological Satellite changes its spin period.As a result,the image matching precision is deteriorated.Based on the movement rule of the VISSR,this paper presents a method to balance the system error in advance by modifying S/DB (Synchronizer/Data Buffer),which can improve the image matching precision trebly and hence intensify the tracking function of S/DB,reaching the international level of the advanced geostationary satellites.This technique is effective in application.