In order to make better and safer use of abundant sea sand resources and alleviate the problem of river sand supply, the effects and mechanisms of different chloride ion content in purified sea sand on the compressive strength, carbonation resistance, sulfate corrosion resistance, corrosion degree of steel bars, chloride ion penetration resistance and electrochemical properties of C40~C70 concrete were studied through large-scale experiments. The results show that when the chloride ion content is less than or equal to 0.150% (mass fraction, the same below), with the increase of chloride ion content, the compressive strength of C40~C70 concrete increases and the later compressive strength continues to increase. At the same time, the carbonation resistance and chloride ion penetration resistance of C40~C70 concrete are also improved. When the chloride ion content is less than or equal to 0.060%, the sulfate corrosion resistance of C40~C70 concrete improves. When the chloride ion content is higher than or equal to 0.150%, the sulfate erosion aggravates. When the chloride ion content is less than or equal to 0.008%, the corrosion of steel bars delays. When the chloride ion content is higher than or equal to 0.060%, the corrosion of steel bars accelerates.