Resource utilization of municipal solid waste incineration fly ash (MSWIFA) is attracting attention, and the pozzolanic activity of MSWIFA is an important property for its utilization. However, there has yet no reliable evaluating methods. Given that fly ash and MSWIFA are both incineration products, borrowing the existing pozzolanic activity methods of fly ash, two types of MSWIFA (from grate furnace and fluidized bed) were tested and analysized by pozzolanic activity test from three perspectives, such as material composition (composition structure analysis method), cementation properties (strength activity index method) and chemical reaction (combined water content method), and compared with the test results of three grades of fly ash. The results show that the composition structure analysis method and strength activity index method are suitable for evaluating pozzolanic activity of MSWIFA, and the combined water content method is not suitable. The amorphous phase silica-alumina content can characterize pozzolanic activity of MSWIFA and correlated with strength activity index. The results of strength activity index method are affected by relation content of amorphous phase silica-alumina content and calcium. The strength activity index of 14 d can characterize pozzolanic activity of MSWIFA, the strength activity index of 90 d or even more curing ages can better characterize pozzolanic activity of fly ash.