The initially designed deposits of the Longdu tailings pool is the mixed tailings of iron ore and covelline. However, the fact that no iron ore tailings have been infused into the pool during its employment directly influenced its stability. By making use of 2D limited meta-softwares, the authors study the seepage features of Longdu tailings pool based on the tested data and material for it. According to first dam penetration, dry slope's length and different atmosphere rainfalls, the seepage field of the tailings pool is analyzed so they can conclude seepage rules for the fine grained tailings pool under different conditions and then study the stability features of the tailings pool. The result shows that change of the deposits gives ill effect on the stability of the pool, and the tailings pool will not run normally if no proper reinforce measure is taken in time.