Abstract: In order to reduce the cost of grouting technology and optimize the grouting materials of mine, based on the cement-clay grouting raw materials commonly used in dynamic water grouting, the grouting material of mine clay-fly-cement composite grout was proposed.The reaction mechanism of grout was discussed through microchemical element analysis.The effects of various factors on solidification time, solidifying ratio and water separation rate were studied by orthogonal test.Through uniaxial compressive strength and flexural strength tests on experimental samples, the optimized slurry ratio was obtained.The results show that the best performance of composite slurry ratio is water solid ratio of 0.8∶1,and the ratios of cement, fly ash, mine clay, lime, sodium sulfate and water quality is 1∶0.45:0.20∶0.05∶0.07∶1.32.Finally, by comparing the mechanical properties of consolidated samples between the optimized grout and ordinary grout, it is shown that the optimized grout has superior properties and can meet the requirements of general grouting engineering.