Abstract: In order to solve the problem of gas overrun frequently occurred at the upper corner of No. 2-512 large mining height face in Sanjiaohe Coal Mine, it used theoretical analysis and field practice to analyze the reason of gas overrun at the upper corner of the working face. Aiming at the problem of gas overrun at the upper corner, it put forward the gas prevention and control measures for high level borehole drainage fracture zone, low level borehole drainage goaf and caving zone. The field practice showed that, after the implementation of the above measures, gas concentration was in the range of 0.02 ~ 0.06% in return airflow of NO.2-512 working face, the gas concentration of upper corner dropped to 0.8% below from 0.8 ~ 3%, which effectively solved the problem of gas overrun at the upper corner, and ensured the mine production safe and efficient.