In Qaidam Basin, the Kunlun piedmont zone is an important area of oil and gas exploration, and the lower section of Paleogene Lower Ganchaigou Formation is its main oil-bearing layer. Controlled by the differences in the development of sandstone reservoir, the degrees of oil and gas enrichment showed differences in different belts of Kunlun piedmont zone. In order to clarify the difference and formation mechanism of reservoir of the lower section in Lower Ganchaigou Formation, by using core, wireline logging data and experiment data, this paper analyzed the reservoir characteristics and controlling factors in different belts of Kunlun piedmont zone, such as Qie6 block, Wunan slope belt, Dongchaishan area and Wanxi structural belt. It is believed that the reservoir characteristics in the lower section of Lower Ganchaigou Formation are significantly different in time and space. In Kunlun piedmont zone, the lower section of Lower Ganchaigou Formation develops clastic pore-type reservoirs, and the reservoir's storage space is mainly the primary intergranular pore. There is five genetic types of sandbody in this study area, namely distributary channel, underwater distributary channel, estuarine bar, sheet sand in braided river delta facies, and beach bar in shore-shallow lake subfacies. The dual superposed effects of sedimentary facies and diagenesis result in significant differences in the development of reservoirs in Kunlun piedmont zone. There are average porosity and permeability values of 14.1， and 32.76×10-3 μm2 in Qie6 block, 13.4， and 36.48×10-3 μm2 in Wanxi structural belt, 6.7， and 2.38×10-3 μm2 in Wunan slope belt, and 3.1，and 0.1× 10-3 μm2 in Dongchaishan belt. Under the same burial depth, the differences of sedimentary structure and sandbody scale, are the main reasons for reservoir physical properties' differences in different sedimentary microfacies, and underwater distributary channel had the best reservoir physical properties, followed by estuarine bar and distributary channel, and the physical properties of beach bar and sheet sand are relatively poor. Under the different burial depth conditions, the differential compaction caused by factors such as maximum paleo burial depth and paleo geothermal gradient, is the main factor controlling the reservoir physical properties' difference in Kunlun piedmont zone. The reservoir physical properties in Qie6 block and Wanxi structural belt are the best, followed by Wunan slope belt, and it is poor in Dongchaishan belt.