In order to specify the optimal scope of salinity of irrigation water which could be used for freezing irrigation with saline water, the effect of freezing irrigation with saline water on coastal saline land soil was studied by simulated experiment on soil columns under different salinities of irrigation water. Compared with the pre-treatment samples, the top soil layer (0 -50 cm) of the soil columns treated by the irrigation water of low salinity (8 g/ L, 16 g/ L) was desalinized, while that treated by the irrigation water of high salinity (24 g/ L, 32 g/ L) was salinized. When the frozen layer of soil thawed completely next spring, the top soil layer (0 - 20 cm) of the soil columns treated by the irrigation water of high salinity (24 g/ L, 32 g/ L) showed drastic salinization, while that of treated by the irrigation water of low salinity (8 g/ L, 16 g/ L) did not. Therefore, the top soil layer (0 - 50 cm) showed desalinization by freezing irrigation with low saline water when frozen soil layer thawed next spring. The lower the salinity of irrigation water was, the better the effect of desalinization was. However, in the same situation, the top soil layer (0 -50 cm) showed salinization by freezing irrigation with highly saline water; therefore, the salinization of coastal saline land soil may be worsened if the soil was treated by freezing irrigation with high saline water. The results of the experiment suggest that the irrigation water with a salinity lower than 16 g/ L is optimum for freezing irrigation under the conditions of this experiment.