Abstract: Abstract: There are a large number of salt lakes distributed in Northwest China. The salt lake water is mainly composed of compound brine with multiple ions. The chloride ion shows the highest ion concentration in the salt lakes of Inner Mongolia, and a large area of saline soil is distributed around the salt lake. Due to the harsh climatic conditions and complex soil environment, concrete engineering structures and materials are often suffered from chloride erosion. In order to study the chloride ion erosion mechanism of pumice concrete under dry-wet cycle conditions, the indoor accelerated corrosion simulation test method is applied with pumice concrete and ordinary concrete as the test group and control group to study the mass loss of pumice concrete, the relative dynamic elastic modulus and the maximum depth of chloride ion erosion by chloride salt erosion and dry-wet cycle test in this paper. The nuclear magnetic resonance technology is used to invert the relaxation time T2 spectrum of pumice concrete on 0, 30, 60, 90, and 120 days. According to the relationship between the relaxation time T2 and pore radius, the T2 spectrum distribution can convert into the pore radius distribution. Thus, the 0-100 μm pores of concrete are divided into five grades: micro pores (0-0.01 μm), small pores (>0.01-0.1 μm), mid-small pores (>0.1-1.0 μm), medium pores (>1.0-10 μm) and large pores (>10-100 μm). Based on the comprehensive analysis of porosity, bound fluid saturation and free fluid saturation, the microscopic pore structure of pumice concrete under dry-wet cycles is analyzed. Moreover, the X-ray diffraction phase analysis and scanning electron microscope analysis are conducted on the internal microstructure of pumice concrete after chloride erosion to investigate the resistance to chloride ion erosion of pumice concrete. The results show that the mass loss rates of pumice concrete and ordinary concrete are consistent with the trend of relative dynamic elastic modulus under the action of chloride salt erosion; the maximum chloride ion erosion depths of pumice concrete and ordinary concrete increases with chloride salt erosion; with the level of chloride salt erosion upgrading, the spectral areas of pumice concrete and ordinary concrete gradually increased; the pore radius ranges of the first and second peaks of pumice concrete decreased, while that of the third peak increased; the pore radius ranges of the first and third peaks of ordinary concrete increase, while that of the second peak decreased; the pumice concrete erosion damage is mainly caused by large pores and cracks which are developed from the small and mid-small newborn pores, whereas the ordinary concrete erosion damage is primarily induced by the micro and small pores developing towards large pores and cracks. After chloride salt erosion, both pumice concrete and ordinary concrete produce a variety of corrosion crystals represented by Friedel salt. This paper can provide a theoretical basis for pumice concrete in the construction of agricultural water conservancy under the environment of chloride salt.