The layout of the stope in an ore block is directly related to the efficiency of ore extraction and determines the production capacity of the mine. The stability of the ore extraction tunnels, as well as the safety of the ore extraction equipment and workers, are key factors in the mining process. This study addressed the practical problems in the upward horizontal approach mining process of the thick and large ore body at Xiaodonggou Gold Mine, such as low ore extraction efficiency, poor stability of tunnel roof, and significant damage to the support structure. An optimized layout plan for the approach in thick and large ore bodies was proposed. The extraction tunnel was aligned along the strike of the ore body, positioned at the ore body boundary. The approach layout on both sides of the tunnel was adjusted to a one‐sided layout, and the route was changed from following the ore body’s strike to a vertical layout relative to the ore body. The results indicate that after optimizing the stope layout, the ore extraction efficiency improved. Numerical simulation results show that, compared to having approaches on both sides, the one‐sided approach layout has less impact on the stability of approach 1#. When both sides of the approach are advanced by 3 m, the roof displacement of approach 1# increases by 64 %. For the one‐sided layout, when advanced by 3 m, the roof displacement of approach 1# increases by 22.58 %. The study provides a theoretical reference for the stope layout in the upward horizontal approach mining of thick and large ore bodies.