The strength-effect of reactive mineral powder such as fly ash(FA),slag(PS) and silica fume(SF) used in heat cured cementitious materials were studied.The main factors affecting the strength-effect of reactive mineral powder were investigated.The results indicate that the unit strengthening coefficient varies with the increasing content of reactive mineral powder by various tendency.The strength-effect of FA under heat curing condition greatly differs from that of samples under standard curing condition.Low water binder ratio condition is advantageous in improving the strength-effect of reactive mineral powder.Furthermore,its strength-effect can be divided into two parts: densifying effect and water-reducing effect,and the former is more evident than the latter.