In order to study the hydraulic fracture characteristics of cement mortar under sulfate attack, four test conditions were designed using a three-field coupling test system. The mechanical properties and hydraulic fracture resistance of cement mortars in sulfate solutions with different pH values and with different erosion times were analyzed. The experimental results show that the cement mortars in sulfate solutions with different pH values has different effects on the mechanical properties of hydraulic fracture. In the later stage of erosion, the deterioration degrees of hydraulic fracture properties of mortar in the 0. 1 mol/L Na₂SO₄ solution with pH values of 7, 3 and 1 gradully decrease. It was found that the hydraulic fracturing resistance of cement mortar under sulfate attack has a significant cubic function relationship with the erosion time.