Abstract: In order to carry out safety control and accident prevention for the operation of the slag dump, the safety level of the slag dump is evaluated. Based on the grounded theory, 73 basic data of waste slag yard were coded, and the three-level coding results were obtained. 21 categories were selected as the index layer of safety evaluation of waste slag yard, and 5 influencing factors such as natural conditions, physical properties of waste slag, waste slag yard, slope and management were selected as the criterion layer of safety evaluation of waste slag yard. Then, the improved AHP method is used to determine the subjective weight, the entropy weight method is used to determine the objective weight, and the difference coefficient method is used to determine the comprehensive weight of the index. According to the existing technical regulations, the safety level is summarized and the evaluation standard cloud is drawn. The safety level of the abandoned slag yard is obtained by using matlab combined with the cloud model. Finally, combined with the case evaluation results and the actual situation, the suggestions for preventing safety accidents in the operation of the slag dump are put forward. The results show that the case application of the safety level of the waste slag yard of the model is consistent with the actual situation, which verifies the rationality of the index system and the effectiveness of the evaluation model, and provides reference for the managers of the highway waste slag yard project.