Abstract: The micro seismic monitoring results showed that unreasonable design of coal pillar was an important reason of rockburst in Longjiapu Coal Mine. In order to determine the reasonable section coal pillar of working face and reduce the threats of rockburst to safety mining, it studied the stress distribution of section coal pillar and downhill coal pillar in Longjiapu Coal Mine by numerical simulation. The simulation showed that it was easy to gather a large number of elastic energy in the coal pillar and form a shock nuclear for unreasonable coal pillar width, which suddenly became instable and induced strong rockburst by mining disturbance. The reasonable section coal pillar width was 6 to 12 m, and the downhill coal pillar width was 120 m at least in Longjiapu Coal Mine.