In order to determine the optimal support mode and support parameters of the mining roadway in the first mining face of a mine, the numerical simulation method was used to simulate the plastic zone distribution and surface displacement under the condition of unsupported rectangular roadway. Through the analysis of the stress and plastic zone distribution of the surrounding rock in the rectangular roadway, it was found that the roof, floor and the middle of the two sides were the most seriously damaged in surrounding rock, and the damage extended deep in the surrounding rock perpendicular to the surface of the roadway. The maximum expand was the two sides, and the roof and the floor of the roadway were similarly extended, and the bottom corner was not damaged. The analysis of the displacement of the roadway showed that the displacement of the two sides and the roof of the rectangular roadway was large, and the displacement of the bottom plate was very small, which was consistent with the analysis of the distribution law of the stress and plastic zone of the surrounding rock. Therefore, it was considered to support the two sides and the roof. Measures were not taken to control the deformation of the roadway of the bottom plate. Although the degree of damage of the two sides of the roadway was different, the difference was not large. Therefore, in order to simplify the design of the support, the two sides adopted the symmetrical support method and achieved good support effect.