Selecting the suitable mining method in consideration of the surface subsidence and the safety of stope and the mining recovery rate under mining and geological conditions of the object is very important for safety mining and protection of surface structures and the least loss of coal. In this paper, we numerically investigated the suitable mining method in consideration of the surface subsidence and the safety of stope and the mining recovery rate by using FLAC3D and Surpac software with a change of stope pillar size in case of mining thick coal seam with dip of 30° by using the different room and pillar methods in depth 97 m from surface. First, we construct 3D block model using FLAC3D software. Then, using numerical simulation analysis of the room and pillar coal mining method with different pillar width and pillar spacing, the generalized Hooke-Brown failure criterion was used to analyze the fracture development, surface subsidence characteristics of rock mass around stope, and extraction rate. As a result of analysis, we proved that the stope safety is ensured and the maximum subsidence of surface is about 2.2 mm in strike and dip direction, respectively, and the mining recovery rate is about 86% in conditions of stope pillar size which is 2 m and between stope pillars is 4 m. We introduced the result of analysis in KaeChon coal mine and proved its reliability.