Abstract: Fly ash is a momentous industrial solid waste produced in the process of coal combustion,with huge output. The storage of fly ash not only occupies the pile lands,but also causes a series of environmental problems. Currently,fly ash is mainly utilized as the construction materials in China,which has low economic value. The total amount of SiO_2 and Al_2O_3 in fly ash is more than 80%. The preparation of porous catalytic materials from fly ash can realize the resource utilization of high added value of fly ash. However,due to the high thermal stability and poor moldability of the original fly ash,the original fly ash needs to be modified. In this review,the fundamental physical and chemical properties of fly ash were introduced firstly,including the elemental composition,crystal phase structure and particle size distribution. Then,the current modification methods of fly ash were described in detail,including the preparation of catalyst carriers and molecular sieves. Acid modification,alkali modification and plasma modification methods are frequently used in the process of original fly ash direct modification to obtain catalyst carriers. One-step hydrothermal,two-step hydrothermal,alkali fusion-hydrothermal and microwave-assisted hydrothermal are generally used for the preparation of molecular sieves from fly ash. Besides,the application fields of fly ash-based catalysts were briefly introduced,consisting of organic degradation,organic synthesis and inorganic gaseous pollutants removal. Organic degradation mainly includes photocatalytic and non-photocatalytic reactions,and organic synthesis mainly includes catalytic polycondensation and esterification. The inorganic gaseous pollutant removal is mainly about denitration and mercury catalytic oxidation. It is found that fly ash exhibits good developing potential as catalyst carrier materials. However,the conventional modification methods have their own advantages and disadvantages,and the technology is still not mature enough,and some further research is needed. Besides,the modification methods of fly ash need to be optimized according to the actual catalytic requirements. Finally,some suggestions for the developments of fly ash-based catalysts were presented,which could provide acknowledgment for the subsequent high-value utilization of fly ash and the related research of fly ash based catalysts.