Located in North Qilian Mountains, Qinghai Province, Zhongnangou belongs to alpine meadow landscape. It has evident alpine-gorge incision and well-developed vegetation below slope, which are obviously unfavorable for granule mechanic motion. Studies indicate that transformation trends of the metallogenic elements in stream sediments of diverse granule grades are identical. The metallogenic elements decrease rapidly in quantity, and are concentrated in the fine size fraction, mainly in the form of sulfide facies. Researches also indicate that the conventional measuring methods for stream detrital sediments have the following defects: granule motion is restrained due to well-developed meadow; stream detrital sediments appear only in Grade 2~3 drainage, and hence much mineralization information might be lost at the reconnaissance stage; at the detailed investigation stage, it is very difficult to collect samples in the real stream sediments due to their limited distribution; where slope sediment samples are collected to replace stream sediment samples, the problem of non-unification of sampling media will occur.