Abstract: Based on the resistivity method, the study focused on exploring the rule of hydration characteristics of alkali-activated fly ash-cement (FAC) composite gel materials at room temperature. The response mechanism of the liquid phase and solid phase was analyzed by combining pH test, FTIR test and SEM test. The results show that the alkali activator accelerates the hydration process, while the hydration stage can be roughly divided into dissolution-crystallization stage, induction-coagulation stage and polymerization-compacting stage. When the fly ash content is up to 40%, the N(C)-A-S-H gel structure in the FAC slurry tends to be silicon-rich with the increase of alkali equivalent, and at 28 days of age, the slurry shows higher compressive strength, richer gel phase content and denser hydration system at 4% alkali equivalent. The change of the resistivity curve of FAC slurry shows the result of the dual influence of liquid phase and solid phase, and the initial hydration stage is mainly controlled by the ionic concentration of liquid phase. In the later stage of hydration, the change of the resistivity curve is much more dependent on the change of the solid phase structure. It will provides theoretical support for scientifically controlling and predicting the structural formation and properties of alkali-activated fly ash-based concrete.