Abstract: Cracking in concrete protective layer due to dowel bar corrosion is one of the important influence factors for the durability of cement concrete pavement structure. Based on the eXtended finite element method, a fracture theory model, which can consider the coupling effects of corrosion product and concrete protective layer fracture, was established and verified in this paper. The initialization and growth of smeared cracks in concrete protective layer were simulated. Then the numerical results were employed to investigate the dowel bar deterioration reason due to corrosion expansion. It has shown that the numerically predicted crack mode agrees well with the in-situation experimental results in de-icing salt environment. The numerical results based on the verified model demonstrate that the dowel looseness accounts for the main reason about steel depassivation and heavily corroded, but it has no significant effect on corrosion product. It can also be concluded that the significant reason of deterioration of dowel bar is the crack formation in concrete protection layer caused by corrosion product volume expanding.