The paper deals with contents, composition, characteristics and distribution of liumua in loessial soils of northwest China. Results obtained are summarized as follows. 1. Distribution of humus contents of soil was getting lower from southeast to northwest. 2. The contens of humic acid, HA/FA ratio and aromaticity of humic acid were high in the light dark loessial soil under steppe vegetation in Jingbain County of Shaaxi Province, and getting decreased westward and northward to the brown pedocal and white cultivated ioessial soil under the vegetation of desert steppe, and decreased southward to manured loessial soil and cinnamon soil under forest steppe and forest vegetation, also decreased eastward to yellow cultivated loessied soil. But the contents of humin was getting increaed westward, northward, southward and eastward. 3. if dark loessil soil was considered as a centre, humic acid combined with Ca were getting decreased gradully from the centre to west, north, south and east, humic arid combined with Fe, Al was getting increased from the centre to west, north, south and east. 4. Aromaticity of humic acid was in the order: steppe foils>arid steppe and forest steppe soils > desert steppe and forest soils.