For decreasing sodium chloride consumption and pollution, the possibility of decreasing concentration of NaCl in the rapid chloride migration coefficient test (RCM) is studied when decreasing NaCl solution from 10% to 3%, 1% and 0.5% by mass, respectively. The chloride-penetration depth and the migration coefficient and electric charge are studied in this experiment. The results as followings: (1) When NaCl concentration is decreased from 10% to 3% in the RCM test, the error is within 5% between migration coefficient values of concrete. It is suggested that a 3% NaCl solution can be used to replace a 10% NaCl solution in Chinese standard GB/T 50082-2009. (2) The content of NaCl solution has a little effect on the electric charge passed. (3) It is not suitable to use the test results of mortar specimens to count conversely the results of concrete specimens, but can use mortar specimens to estimate the performance of different binders.