In order to investigate the effect of dolomite on the sulfate resistance of cement-based materials, the cement paste specimens and cement mortar specimens mixed by 10%, 20%, 30% (mass fraction, the same as below) dolomite were soaked in 5% MgSO4 solution and 5% Na2SO4 solution at low temperature, and sulfate attack test was carried out. Changes of the macroscopic morphology of specimens were observed regularly, and the erosion products were quantitatively analyzed. Flexural strength and compressive strength of cement mortar specimens were measured for macroscopic analysis, and the effects of different types of sulfates on the formation of thaumasite were obtained. At the same time, the effect of dolomite on the products of cement cementitious system was investigated by thermodynamic simulation. The results show that when the dolomite content is 10%~20%, the formation of thaumasite is inhibited, the sulfate resistance of cement-based materials is greatly improved, and the flexural strength of cement mortar specimens is significantly improved， which is consistent with the result of thermodynamic simulation.