Abstract: Based on the conditions of deep open pit of Guilaizhuang gold mine, the static safety factors of open pit slope were obtained by the FLAC software according to the principle of the strength reduction method. The explosive loading was imposed on the open pit bottom to analyze the dynamic stability of the slope under different reduction factor. The theory of load-unload response ratio (LURR) was introduced to establish a load-unload response model of slope under blast loading. The periodical variation of blasting vibration velocity was regarded as loading parameter, and the velocity of characteristic point was regarded as response parameter to determine the LURR of slope under blasting loading. It was found that the LURR under blast loading can reflect the different slope stability state, and the LURR increases gradually as the slope approaching instability. Therefore, LURR is regarded as a very effective nonlinear dynamic analysis method to judge slope stability.