The structural evolution, sedimentary characteristics and source rock characteristics of Minle Basin and Jiuquan Basin have certain similarities, but the exploration degree is very low, which is in the stage of regional exploration. In this paper, the Cretaceous source rock system is studied in Minle Basin. Through field outcrop, drilling sampling and sample analysis and testing, combined with geophysical data analysis, the geochemical and plane distribution characteristics of Cretaceous source rocks were clarified, and the potential analysis of oil and gas resources was carried out. The results show that : 1 Two sets of lacustrine dark gray, gray-black mudstone and shale are developed in the lower and upper Cretaceous formations in the Minle Basin, and the organic matter abundance of the two sets of source rocks reaches the standard of better continental source rocks. The organic matter type of the source rock is mainly type II. The maturity of the source rock in the lower rock group is high, and the lower part of the upper rock group reaches a mature state and has hydrocarbon generation potential. The source rocks of the lower rock group and the upper rock group are distributed in the three sags, and the closer to the center of the sub-sag, the greater the thickness of the source rocks. 3 The evaluation results of oil and gas prospect areasThe Yangfangxiang area in the southeast of Lizhaicun sag and the Laorenba area in the eastern margin of Zhangye sag are Class I prospective areas. The southern part of the Zhangye sag, the northern part of the Chaoyuansi sag, and the southern part of the Lizhaicun sag are Class II prospective areas ; the Sangongxia area in the southwest margin of the Zhangye sag and the Ganjunzhen area in the northwest margin of the Zhangye sag are Class III prospective areas.