The study area is located in Heishan area of Golmud in Qinghai Province. Its surface is covered with a large quantity of eolian sand and loess, and hence this area h is not suitable for soil and detritus sampling. An infilling 1:25 000 stream sediment survey method was used in early geochemical prospecting. The sampling density is 40 samples per square kilometers and the sampling grain size is -10-+40 mesh. Through analyzing the content, distribution and combination characteristics of elements, the authors hold that the contact zone between the intrusion and the first member of Tanjianshan Group in the study area has a good potential in search for polymetallic deposits. According to the above geochemical evidence, the authors delineated 5 comprehensive anomalies and subsequently evaluated them. Two ore-bearing skarn belts were found, which are confined in the range of AS4 synthetic anomaly. Two Cu-polymetallic orebodies were preliminarily determined in No. 1 ore-bearing skarn belt. The results show that the infilling 1:25 000 stream sediment survey method has favorable effects in ore prospecting at desertification mountainous plateau land surrounding the Qaidam Basin.