In this paper the effects of low molecular weight polyacrylamide on soil saturated hydraulic conductivity, water characteristic curve and horizontal diffusion rate of saline soil were studied. The results showed that with the increase of the content of polyacrylamide used in soil, the saturated hydraulic conductivity decreased gradually. Under the same soil water suction, the water capacity reached the maximum when 0.25 g/kg polyacrylamide applied in the slightly salinized soil, and as to moderately and severely salinized soil, water capacity reached to the maximum when 0.5 g/kg polyacrylamide applied. Under the same soil water content, with the increase of polyacrylamide, soil water horizontal diffusivity decreased and the magnitude of this reduction increased with the increase of the degree of salinization.