In order to ensure the systemic error correction of regional geochemical data more according with to the geological reality, the relationship between geological background and regional geochemical data is studied. The conclusion has been drawn that regional geochemical data of congeneric geologic bodies in uniform geologic background originated from the common population and have similar characteristics. The method of the systemic error correction of regional geochemical mapping data based on geological background analysis is proposed. The application of the method to map-serging of three Ag element regional geochemical maps of 1∶200 000 confirms that the systemic error correction is available and favorable to both interpretation and application of regional geochemical maps.