A research of low temperature sulfate/chloride attack was carried out to investigate the effect of chloride ion on thaumasite form of sulfate attack(TSA). The samples of cement based materials with limestone powder added were immersed in NaCl/Na2SO4 mixed solution with different mix proportions(by mass) at (5±2)℃. The appearance of sample was observed, its strength was tested. Besides, the corrosion products were analyzed by infrared spectrometry(IR) and X ray diffraction(XRD). The results show that the TSA in the sample immersed in pure Na2SO4 solution takes place, spalling of the sample from external to internal occurs, and the gelling property of the sample is lost. However, TSA erosion degree of the sample immersed in NaCl/Na2SO4 mixed solution gradually reduces with increasing chloride ion mass concentration. Chloride ion can slow down TSA process by reducing thaumasite formation rate. The effect of chloride ion on TSA can be divided into three stages:inhibition stage, decline stage and failure stage.