Abstract: In order to analyze the influence of high-low pressure mixed drainage on drainage negative pressure and to better guide the mine production process of gas extraction,drainage negative pressure was taken as reference index.Adopting comparative analysis method,a determination study of Zijiang coal mine was carried out.The test results showed that negative pressure of borehole under high-low pressure separated drainage status can reach to 11.14 kPa on average,it was increased 9.28 times than that was in high-low pressure mixed drainage status;the negative pressure of ground pump can reach to 70.25 kPa on average,it was increased 3.42 times than that was in high-low pressure mixed drainage status.