The stability of the strata of a coal mine is seriously affected by the underlying worked-out area, which frequently causes deformation or even collapse, depression and geofracturing and hence gravely threatens the buildings above it. For the purpose of consolidating the rock and soil bed, drill-hole grouting has often be used to plug the worked-out area and fractures of the rock and soil bed. In this paper, the principle of applying ultrasonic wave method to detecting drill-hole grouting quality is described and the test result is analyzed.