In order to determine the development height of water conducting fracture zone in 150313 fully mechanized top coal caving face of Yinying Coal Mine, numerical simulation and field measurement methods are used to study the deformation characteristics of overburden.The numerical simulation results show that the caving zone height of 150313 working face is about 26 m, and the caving mining ratio is 3.59; the development height of the fracture zone is 85.8 m, and the fracture mining ratio is 11.87.Three distributed optical fiber monitoring boreholes are arranged for the underground observation test of the height of the water conducting fracture zone of the working face, and the BOTDR technology is used to test the deformation characteristics of the overburden during the mining process of the working face.The monitoring results show that the distributed optical fiber monitoring technology can accurately monitor the deformation and movement characteristics of the overburden, and test the height of the “two belts” of the overburden.The layer of the point or breakpoint with large optical loss of the sensing optical cable corresponds to the height of the fracture zone of the working face, and the position of the critical strain for crack initiation corresponds to the height of the fracture zone of the working face.The field test results show that the height of overburden caving zone in 150313 fully mechanized top coal caving face is 28.51 m, and the caving mining ratio is 3.94.The height of the water conducting fracture zone is 75.44 m, and the fracture mining ratio is 10.43.The research results can provide reference for the prevention and control of roof water disasters and the protection of water resources under similar conditions.