With the drill hole ZK23-2 as the object and the microscopic slice identification and the geochemical analysis of fluid inclusions of the ore-forming period as the main means, this paper mainly studied wall rock alteration of the No. 302 uranium deposit,. The results show that the ore deposit has a variety of alterations, which are composed of such types as alkali feldspathization, silicification, sericitization, hematitization, chloritization, epidotization, carbonation, and kaolinitization. The ore deposit shows obvious vertical and horizontal zoning. From the top to the bottom of the ZK23-2 drill hole, four alteration zones were recognized, i.e., red-sericitization zone→silicification-intense red alteration-sericitization zone (uranium enrichment zone)→chloriti-Zation-sericitization zone→ weak alteration or normal granite zone. Major elements, trace elements and rare elements in the rock show regular variations. The altered rock has preserved the same geochemical characteristics as the ore-hosting Changjiang rock body, as can be seen from the consistency of their distribution patterns of trace elements and rare elements. Homogenization temperatures of fluid inclusions in different alteration zones are all below 220℃, belonging to moderate-low temperature hydrothermal fluids. As for chemical components of fluid inclusions, inert gas N2 appears at all the alteration zones, and gaseous CO2 exists in the strong alteration zone, suggesting that the dissolution, migration and enrichment of uranium were related to gaseous CO2 and occurred in gaseous N2 environment during the formation of the uranium deposit. In addition, a study of fluid inclusions in the ore-forming period shows that characteristics of different wall rock alteration zones might have resulted from the mixture of ore-forming hydrothermal fluids.