Abstract: The sandstone hosted uranium deposit located in northern Ordos Basin, China contains abundant carbonate minerals, with its average content between 2% to 5%. Due to high content of carbonate, during in-situ leaching of sandstone uranium deposit, the permeability of ore strata would be significantly reduced as the secondary precipitation of carbonate minerals. In this study, through a series of agitation leaching, core flow and column leaching tests, the feasibility of in-situ leaching by the mixed organic acids was researched. The results show that the combination of acetic acid and citric acid with the corresponding volume ratio of 5∶1 has the best leaching result. Such mixed organic acids used in in-situ leaching test can not only leach uranium from ores, but also can improve the permeability of ore strata. In the next mining stage, the acidification enhanced permeability improvement, by mixed acetic and citric acids with volume ration of 5∶1, can thus be adopted for facilitating the CO₂+O₂ in-situ leaching.