The Qianjiadian uranium deposit, located in the southern Songliao basin, is a super- large sandstone- type〖JP〗 uranium deposit. The exposed diabase in the mining area exerts a significant impact on uranium mineralization. However, the precise relationship between diabase intrusion and abnormal uranium enrichment requires further investigation. This study, based on field geological investigations, focuses on diabase and uranium ore samples collected from the Qianjiadian depression. A comprehensive suite of analytical techniques was employed, including petrography, electron probe microanalysis (EPMA), scanning electron microscopy (SEM), major and trace element analysis, in- situ U- Pb dating of uranium minerals, zircon U- Pb dating, in- situ carbon- oxygen (C- O) isotope analysis of minerals, and fluid inclusion studies. EPMA revealed the presence of grid- like, titanium- bearing uranium minerals within the ore, indicative of high- temperature genesis. Fluid inclusion analysis of carbonate cement and calcite veins in ore- bearing sandstone and diabase indicated fluid interactions characteristic of medium to low temperatures. In- situ C- O isotope compositions of minerals suggest the influence of high- temperature magmatic hydrothermal fluids on the ore- bearing rocks. Lithological characteristics of mudstone and sandstone further support the presence of magmatic hydrothermal fluids and volcanic ash (debris). High- resolution SEM analysis identified distinct contents of high- temperature elements (Pt, Os, Re) in nativegold particles, brannerite deposits, and pitchblende deposits, suggesting diverse origins. These findings strongly suggest that the thermal effects and deep- sourced mineral contributions associated with the Qianjiadian uranium deposit are related to diabase intrusion. Geochemical characteristics and LA- ICP- MS zircon U- Pb dating of the diabase reveal a tholeiitic composition with a formation age of 41. 6±0. 78 Ma. This Late Eocene magmatism, originating from the transitional mantle, intruded and crystallized in the shallow crust, forming diabase. The intrusion provided heat, deep- sourced mineral components, and associated metallic elements, greatly enhancing the rate and scale of uranium enrichment. A strong spatiotemporal correlation exists between the thermal effects of different series of diabase intrusions and the multi- stage mineralization of the uranium deposit. The Eocene period (40~53 Ma) represents the stage where diabase intrusions played a major role in uranium mineralization. Overall, the Qianjiadian uranium deposit in the southern Songliaobasin is a “multi- genesis compound mineralization” deposit, characterized by multiple genesis, diverse sources, and multi- stage mineralization processes.