Aiming at the stability of protective coal pillar in industrial square under the influence of mining, the protective coal pillar of industrial square in Xiaojihan Mine of Shaanxi Huadian Yuheng Coal and Electricity Co., Ltd. was taken as the background, the influence of adjacent working face mining on the protective coal pillar of industrial square was studied by FLAC3D numerical simulation software. The research showed that after the mining of the working face adjacent to the industrial square, the corresponding surface subsidence displacement in the middle of the working face was the largest, and the maximum displacement was close to the mining height. The horizontal displacement at both ends of the working face was larger, especially the horizontal displacement on the side of the goaf was the largest. When the width of the protective coal pillar was greater than 30 m and the width of the strike protective coal pillar was greater than 60 m, the movement and deformation of the buildings in the industrial square were within the allowable range of the specification. The actual width of the protective coal pillar in the downhill of the industrial square of the mine (33.8 m) was greater than 30 m, and the 99 m of the strike protective coal pillar was greater than 60 m, which met the requirements. However, considering the recovery rate and safety factor of the coal pillar resources, it was recommended to adjust the width of the strike protective coal pillar to 80 m.