Abstract: Three-step sequential chemical extraction method established by Reference Material Office of former European Community was used to study chemical speciation of 7 heavy metals (Zn,Ni,Pb,Cu,Mn,Cd and Cr) in municipal solid waste incineration (MSWI) fly ash.Results showed Cd that mainly existed in weak acid extractable form (account for 75.66% to 89.09% of the total mass of cadmium),and meanwhile the contents of weak acid extractable form of lead and copper were also very high（account for 32.12% to 41.36% of the total mass）,which had a potential impact on the environment;whereas the contents of reducible and oxidable speciation of Pb,Cu,Mn,and Zn were relatively high;and Cr and Ni mainly existed in residual speciation（account for 57.17% to 86.90% of the total mas）.  