The effect of triethanolamine(TEA) on the initial structure formation and mechanical properties of cement was investigated by the testing of setting time,resistivity,chemical shrinkage,flexural and compressive strengths.The measurements show that two critical adding amounts of TEA are existed(0.02% and 0.15%).TEA can advance the solution of cement and accelerate the hydration of C_3A,but the effect of the hydration of C_3S is related to the amount of TEA.The mechanical strength is advanced by proper amount of TEA.The setting time can be controlled and TEA can be used as retarder or accelerator to satisfy the requirement of different condition.