Abstract: The effect of using mechanical grouting method to seal nearly horizontal holes is poor,which leads to the technical problem of low holes utilization rate.Therefore,the double-phases-grouting hole sealing method is put forward.The process and principle of double-phases-grouting hole sealing method are introduced.Cement mortar’s self contraction effect is explained,and the model of gas leakage through apertures around the holes is established.A test of this method is carried out at the Changcun mine.The results show that the gas concentration is effectively improved after the application of this method,and the mean pure gas quantity is improved by an average of about 25% ~ 40%,and the decay rate is lower.All in all,the goal of high-compactness is achieved.