Ionic rare earth ore is a unique mineral resource in China and rare in the world. It dominates the global supply of medium and heavy rare earth， and has the characteristics of complete distribution， many high-tech application elements and great comprehensive utilization value. However， in the process of ionic rare earth mining， the well wall is prone to collapse， resulting in slope instability. This paper analyzed the calculation model of the critical velocity of the migration volume of the ore body particles under different influence factors. The results show that the critical flow rate of the ore particles increases with the particle radius， arrangement angle and friction coefficient. Electrostatic power is affected by the concentration of immersion liquid， but it has little influence on the migration of ore body particles. In addition， the viscosity of the solution can significantly reduce the critical flow rate. This study can provide theoretical and technical support for the safty and efficient development of ionic rare earth.