Abstract: The preparation of geopolymer from fly ash is one way of green comprehensive utilization. In this paper, research progress was reviewed from three aspects: character of fly ash, affect factors and formation mechanism, focused on the quantitative analysis of glass phase content, hydrolysis and polycondensation of fly ash under alkaline condition. Some problems in the research are put forward, such as the overlapping of hydrolysis and polycondensation, which could be resolved by decreasing the polycondensation reaction rate with chemical process. These researches would provide a direction for the further studies of fly ash based geopolymer.