Abstract: Three compound activators' prescriptions, which are screened out from twenty-four types of reagents that may activate early activity of fly ash with high activation, are prepared by use of the comparison and compound of each activator and orthogonal optimization of activators dosage. The application results of the activators in the high-volume fly ash concrete show that the active effects are good. The active mechanism of the activators is discussed according to the pictures of scanning electron microscopy of slurry of fly ash and cement.