In order to improve the quality of coastal saline soil,the paper took rice straw ash as amendment and studied the variation rule of these indicators such as the content of water-table aggregates, consistency index and compactibility in coastal saline soil at the volume ratios of of 0%,10%,20% and 30% of ash and soil. The results showed that rice straw ash can increase the content of water-stable aggregates with particle size between 5.0mm to 10.0mm and 2.0mm to 5.0mm,and decrease the content of micro-aggregates with particle size less than 0.25mm; rice straw ash can significantly increase liquid limit ,plastic limits and plastic index,it has prominent influence on plastic limit , liquid limit but has less influence on plastic index; rice straw ash can decrease maximum dry bulk density and increase optimum moisture content. The results clearly indicated that application of rice straw ash can improve the property of water retention and porosity of coastal saline soil. The use of rice straw ash can achieve bi-ecological benefit of resource recovery of industrial wastes and rational improvement of soil.