The influence of the raw material on the properties of singlecomponent inert grout for simultaneous grouting is investigated systematically. The influences of the watercement ratio, gelsand ratio, bentonitewater ratio, fly ashcement ratio, admixture FDN3 and silica fume on the properties of the simultaneous grout are studied. The trend of the optimization of the mixing proportions of simultaneous grout is proposed on basis of the study results. This paper can be served as reference for the mixing of simultaneous grout in shield tunneling in the future.