Abstract: According to the high cost and high consumption of the chemical grout in the deep borehole high pressure grouting process of the broken coal and rock mass in the coal mining face,there was a poor binding problems between the rook binding mass and coal mass with the ordinary Portland cement grout.a modified liquid applied to the ordinary Porland cement grout was developed. A lab analysis was conducted on the vwscosity,.calculi rate,8 type model tensile strength,bonding performances of grout binding rock under the bot ulling conition as well as otherophysical and mechanical performances of modified cement base grouting material.The results showed that when the dosage of the cement modfiedliquid was not over 20%,the dosage would have less infuences to the fluidity of the grout and could meet the requirements of the grout for the high pressure deep borehole grouting.Under the condition of the different water and cement ratio,the calculi rate of the grout would be over 98%,themodified liquid would not be obvious to improve the calculi rate of the grout and would not make the calcul f the bolt pulling,the bond performances test showed that when the water and cement ratio was 0.7 ∶ 1.0 and the modified liquid dosage was 1 5%,the bonding performances of the rock binding mass would be best.The high pressure deep borehole grouting would be better to have a singe cement grout,the sodium silicate volume would be 3%～4% of the cement quantity and the dosage of the cement modifed liquid would be 15%~20% of the cement grout quantty.The modified cement base grouting material was applied to the underground mine test of the high pressure deep borehole grouting during the terminal period of N1-3island coal mining face in Lu an Changcun Mine. The sie est showed that the grout consumption volume and grouting cost were highly reduced and the terminal period was shortened.