68 soil profiles were classified according to China genetic soil classification system in the Beijing mountain area, the great group and subgroup names were compared with the name of map delineations in Second National Soil Survey map. Only 18 of them had the same classification names. The reasons of that soil mapping unit names were different from the classification names given by us were: firstly it was that soil scientists named a map delineation according to a soil profile model, not according to the dominant soils; secondly it was that soil scientists classifying soil according to current climatic and vegetation condition not according to soil properties in China genetic soil classification system; thirdly it was that the mapping precision is low. We suggested that soil classification must take soil properties as classification criteria not the soil forming factors; it might get higher precision soil map that mapping single soil properties in the field, overlaying those single soil property maps and classifying the map delineations that have many soil attributes.