Abstract: In order to study the stope stability of close distance layers which is underwater mining in Laohudong phosphate mine,the maximum exposed roof area of stope in two layers were calculated by elasticity method,structural parameters of the upward cut and fill mining method were optimized，and the stability of two mining methods with multiple stopes were analyzed by the software ANSYS.The results show that，the reasonable width of the room should be 6 to 8 m when the stope layout is vertical direction by upward cut and fill mining method.The stope stability is good while meet to the number designed by two methods,and the stope structural parameters designed could satisfy the requirements of safe and efficient mining.

Key words: Close distance phosphate layers, Gentle dip and medium thickness ore body, Underwater mining, Stope stability