Although the measurement of stream sediments has become a relatively mature technology in China, the optimal sampling granularity of stream sediments remains variable in different supergene environments. In this paper, element behavior of different granularity soils and stream sediments in weathering processes is investigated taking the Niutougou gold deposit of the Xiong' ershan gold mine in western Hennan Province as an example. The results show that the weathering degree of soils increases with the decreasing soft granularities. This behavior is also found in the stream sediments and is clearer than that in the soils. Element content shows a stable trend in soils or stream se,,diments when the sample granularity decreases from 4 to 100 mesh ( or 2 - 0.154 mm), but the element content changes sharply when granularity is less than 100 mesh (or 0.154 mm). This sharp change may be resulted from the transfer of weathering mechanisms. Hydrothermal ore-forming dements are concentrated in the 60 - 100 mesh granularity in soils and 80 - 100 mesh in stream sediments, respectively. The sample granularity of 60 - 100 mesh is optimal for the measurement of stream sediments in the Niutougou gold deposit. This granularity of soil or stream sediment samples not only inherits the element behavior of their parent rocks, but also is weathered sufficiently to represent their source rocks and thus to meet the need of decreasing sampling density. The geochemical survey at a scale of 1:50000 was carried out in the Niutougou gold deposit choosing the sample granularity of 60 - 100 mesh, and the results indicate that the concentration centers of elements coincide with the ore blocks in the ore district. This result validates the feasibility of sampling granularity and provides guidance for geochemical surveys in the Xiong' ershan gold mine.