The hydration process of alkali-activator slag(AAS) cementing material was studied by ultrasonic, and AAS’s hydration heat was test too by changing the environment temperature, activator modules. The results show that the hydration process of AAS can be divided into three stages: the initial phase hydrolysis, hydration acceleration period and stable phase. The hydration rate and hydration heat of the AAS materials will remarkably accelerate as the temperature raise. The appearing time of the peak value of the hydration exothermic curve of the alkali activated cementitious material delays as the activator module increases, and the peak value also gradually decreases.