Abstract: In order to solve the problem of late period compressive strength reduce about the traditional cement- sodium silicate double liquid consolidated mass, a theoretical analysis, lab experiment and site observation means were applied to the experiment with the active industrial waste fly ash partially replaced the cement in d ouble liquid system. The experiment studied the 30% ~ 50% fly ash mixed affected to the double liquid setting time and the modification role in compressive strength of the consolidated mass. The study resluts showed that the setting time of the grout was increased to modified fly ash and could relax the too quick setting of the grout. T he active role of the fly ash could improve the late strength of consolidated mass and with 50% fly ash mixed, strength of the consolidated mass after two years could b e improved over 15%.