Abstract: With the improvement of mineral processing technology, the particle size of tailings is becoming smaller and smaller.It leads to weak beach surface of tailings reservoir, the difficulty of dam construction, and even affects the production of enterprises.Combined with engineering practice, this paper adopts the method of "geofabriform method + wide dam" to effectively solve the problem of fine tailings dam construction, analyzes the action of wide roof subdam, and demonstrates the safety and stability of wide dam by numerical analysis method.The results show that the wide roof subdam can protect the unconsolidated tailings in the reservoir.?Mold bag dam body can enhance the bearing capacity of weak dam foundation, accelerate the consolidation of dam foundation, suitable for direct damming on soft foundation;?The stability of the dam meets the requirements of the code.