Based on field experiment, the effects of saline water irrigation capacity under gypsum applied on the distribution characteristics of soil water-salt were studied in the coastal area of north Jiangsu Province. The results showed that irrigation capacity was the crucial factor constraining the distribution of soil water-salt under saline water irrigation with gypsum. With the increase of irrigation capacity, the vertical migration space of humid apex deepened and water contents in humid region increased gradually. The subduction of salt and Na+ on the topsoil occurred at 0-90 cm depth under the irrigation capacity of above the maximal field water capacity, especially significant at 0-20 cm depth which of 29.0% salt and 26.9% sodium ion subduction ratios respectively; While the accumulation of salt and Na+ ion in the topsoil occurred at 0-60cm depth under the irrigation capacity of below the maximal field water capacity, but which weakened with the increase of irrigation amount.