In order to study the influence of sand mining on the stability of river embankment, particle flow code(PFC)was used to monitor and analyze the influence of three parameters, namely, the shape of sand mining pit, the distance from the foot of the dike and the depth of sand mining pit, on the stability of the dike. The change regularity of the porosity of the materials used to build the dike with the parameters of sand mining pit was obtained. Based on the principle of strength reduction method and the method of characteristic point displacement criterion, the safety coefficient of anti-sliding stability of the embankment was calculated, and the internal relation between the way of sand mining in river channel and the anti-sliding stability of the embankment was obtained. The results show that the change of porosity can reflect the change of soil mesoscopic particles, the porosity can be used to track the loss and destruction process of the soil body in various parts of the embankment under different sand mining conditions. The way of sand mining in river channel has a great influence on the anti-sliding stability of the embankment. The closer the sand mining pit is to the foot of the embankment, the lower the safety coefficient of the anti-sliding stability of the embankment is. Therefore, a sufficient safety distance should be kept between the sand mining pit and the foot of the embankment in the normal design.