In order to study the stress distribution and evolution law of coal pillars along the working face in front of the 103下01 working face of Sitai Mine of Datong Mining Group, the FLAC3D numerical simulation software was used to simulate the working face. The stress distribution of coal pillars was at 60, 120, 180, 240, 300, 360 m. The results showed that the peak stress of the coal pillar in the working face was stable at 40 MPa after the working face mined for 180 m, and the stress of the coal pillar behind the working face was 180 m, when the stress on the coal pillar was 80 MPa at most. After the surface was advanced to 240 m, the stress peak became smaller and stabilized at 60 MPa. The KJ550 stress online monitoring system was used to monitor the stress of the coal pillar in front of the working face. The numerical simulation and the on-line monitoring of the KJ550 stress showed that the peak of the stress on the front of coal pillar and the rear coal pillar were compared when the working surface mined 240 m, the peak stress on the front and rear coal pillars of the working face was stable, which may cause less coal burst.