The influence of ground granulated blast furnace slag (GGBFS) on the early hydration of calcium aluminate cement (CAC) at 20 ℃, 35 ℃ and 50 ℃ were investigated in this study. The test on setting time, compressive strength, electrical resistivity, internal temperature of cement pastes and hydration products were employed. The results indicate that the addition of GGBFS reduces chemical shrinkage at 72 h and decreases the peak value of the rate of chemical shrinkage. The electrical resistivity curves and the chemical shrinkage curves show an obvious phase transformation stage and induction stage respectively at 20 ℃. At 35 ℃, the setting time of cement pastes is prolonged, the development of electrical resistivity is inhibited after the addition of GGBFS. At 50 ℃, the electrical resistivity decreases significantly near 24 h and the setting time of cement pastes are shortened obviously. However, the reduction of electrical resistivity at 24 h is undermined with GGBFS. Besides, the hydration products and compressive strength of CAC and GGBFS composites are affected significantly by the curing temperature. At 20 ℃, the incorporation of 40% (mass fraction) GGBFS reduces the amount of CAH10, decreases the compressive strength of cement pastes. At 35 ℃ and 50 ℃, the hydration products at 1 d are major C2AH8 and minor C3AH6, the reduction of compressive strength are weakened with GGBFS. At 28 d, the addition of GGBFS can promote the formation of C2ASH8 at different curing temperatures.