Abstract：Regional geochemical data contain abundant geological information and can be used in regional geological mapping in shallow overburden areas. The relationship between the chemical composition of stream sediments and bedrocks in shallow overburden areas is studied and the method of inferring the chemical composition of bedrocks is proposed by using the oxide composition of stream sediments and the chemical composition of regional rocks as the constraint. According to the mass balance between the chemical compositions of stream sediment and its minerals, the inference method of the mineral composition of bedrocks is presented. The compilation method of inferring geological maps according to the regional geochemical data is put forward and is tested in the typical forest-swamp overburden area and the validity of the method is verified by geological survey and drilling. Thus making full use of regional geochemical data to extract geological mapping information is a valid approach to improving the geological mapping quality in shallow overburden areas.