Abstract: The numerical simulation on the stratum movement law during the downward filling-mining process of steep and extremely narrow orebody in Cuyu gold mine was carried out. The joint strike and spacing is determined through on site investigation. The Hoek-Brown strength criterion was used to determine the numerical calculation parameters， and the boundary conditions of numerical calculation was obtained by the neural network. was used to optimize the neural network to obtain the boundary conditions of numerical calculation. The stratum movement law during underground mining of steep and extremely narrow orebody was carried out by three different numerical calculation methods. The research showed that the settlement of the rock mass on the upper part of the orebody is obvious， and the settlement area of the overburden rock in the orebody is cylindrically collapsed. According to the calculation results of FLAC3D and 3DEC， there is no settlement area on the surface in Cuyu gold mine. The No. 2 shaft， the newly-built concentrator and the staff dormitory bath are all located outside the rock transfer belt based on the calculation results of random medium method. Compared with FLAC3D and 3DEC calculation， the random medium method is more suitable for simulating the rock strata movement caused by the steep and extremely narrow orebody mining.

Key words: rock mechanics, steep and extremely narrow orebody, backfill mining, rock strata movement, numerical simulation