[en] To investigate the release law and mechanism of uranium form the uranium tailings under simulated rainfall, the method of semi-dynamic leaching of uranium tailings was adopted to investigate the leaching characteristics and uranium tailings leaching residue was analyzed by SEM and XRD. The results of semi-dynamic leaching process showed that the release rate of uranium decreases with increasing leaching time. With the pH of leachate increase, the cumulative release amount of uranium gradually decrease, but the different of pH influence on uranium cumulative release amount is not significant ,the release of uranium is from the mineral surface adsorption of uranyl sulfate complex dissolved in the process of the formation of dihydrate gypsum and adsorption of uranium complex released by leaching solution. (authors)