Abstract: The discovery of the Qianjiadian-Baixingtu uranium deposit (QBUD) in the Kailu basin extremely encourages explorers to look for in-situ leaching uranium deposits (ISLUD) in the post-Jurassic extensional basins in Northeast China. There is a well-developed faulted system in and near QBUD. The famous Xilamulun River fault passes through the deposit. Diabase related to regional faults is extensive throughout QBUD. It is estimated that 70%~80% of the exploration drilling holes meet the diabase beds. The cystic and lenticular orebodies in QBUD conflict with the interlayered oxidation genesis, which holds the generation of rollfront or tabular orebody. The core observation, microscope, electronic microprobe and inclusion temperature and salinity provide three kinds of evidence. Firstly, the heat from the diabase intrusion causes the hardness of the wall rocks, and a great number of new cement minerals are precipitated from hot fluid flows. Secondly, carbonate veins penetrate strata in handy specimen or under microscope. The clasitc grains in target sandstone are strongly altered by hot fluid flow. Further studies reveal three stages of carbonate minerals:1st stage calcite, 2nd stage ferrous dolomite and 3rd stage high ferrous dolomite. Thirdly, there are three peaks for the inclusion temperature, 80~90℃, 110~120℃ and 140~150℃, respectively, and three ranges of inclusion salinity 5.0%~10.0% NaCl, 10.1%~15.0% NaCl and 15.1%~20.07%NaCl. They are in accord with three stages of hot fluid flow processes.