In order to study the reasonable interval coal pillar width of the three-face empty island working face, the island face of Hejiata Mine was taken as the background, the numerical calculation simulation analysis method was used to study the evolution law of stope stress and displacement during the mining process of the island working face. The numerical calculation models of coal pillars under three working conditions of 15 m, 20 m and 25 m were established to study the characteristics of stress field and displacement field under different interval coal pillar widths, and then the reasonable coal pillar width was determined. The results showed that during the mining process of the island working face, the stress concentration area of the stope was gradually transferred from the roadway protection coal pillar to the interval coal pillar. When the width of the interval coal pillar was too small, the displacement of the coal pillar increased sharply, and the chain failure of the roadway protection coal pillar was caused. When the coal pillar was separated by 15 m, the internal stress peak was 39.8 MPa, and the displacement peak was 1.09 m. The overall stability was poor, and it was difficult to support the roof to maintain the safety of the working face. After increasing to 20 m, the stress environment and displacement were obviously improved, the peak stress was reduced to 37.9 MPa, and the displacement extreme value was reduced to 0.71 m. There was a certain elastic core area inside which could play an effective supporting role. When the width of coal pillar was 25 m, the decrease of stress and displacement was small, and the stability was further improved. In order to ensure the safe mining of the working face and the efficient utilization of resources, the width of the interval coal pillar could be 20 m. After engineering practice, the maximum displacement of the roof and side of the island working face was only 73.6 mm and 41.8 mm, which could ensure safe and efficient mining.