Solidification/stabilization technology is widely used in remediation of heavy metal contaminated sites. Carbon dioxide carbonation can change the chemical dissolution behavior of pollutants in heavy metal contaminated clayey soil solidified. Taking the lead-contaminated soil as the research object,the relationship between lead concentration and pH value in leaching solution was measured by acid/alkali titration test and pH related dissolution test. Five fractions of chemical occurrence of lead were determined by sequential extraction procedures. The change of chemical dissolution characteristics of cement solidified heavy metal contaminated clay and the relationship between the dissolution of heavy metal pollutants and pH value under carbonization were studied. The results show that the acid/alkali buffering capacity of solidified contaminated soil decreases by 18.5%-72.4% under carbonation. The relationship between the solubility of lead and pH value shows the behavior characteristics of amphoteric substances. The solubility of lead is relatively small when the pH value is between 7 and 11, and it is larger when the pH value is less than 7 or more than 11. The chemical occurrence forms of lead in the solidified contaminated soil are mainly Fe-Mn oxides bound phase. Under the action of carbonation, the proportion of exchangeable phase and carbonate bound phase of cement stabilized soil increases by 4.3% and 3.5% respectively, while the proportion of Fe-Mn oxides bound phase, organic matter bound phase and residual phase decreases by 2.1%, 0.9% and 4.8% respectively. Under the combined action of acid rain and carbonation, lead in cement stabilized soil is more easily dissolved.