For further studying on the physicochemical mechanism of interior Characteristics of a special clay such as the coastal saline soil, an experimental research is conducted on a seaport saline soil foundation improvement project on Bubiyan Island, Kuwait. On the basis of field vane shear test, triaxial test , direct shear test, Atterberg limits test, mineral composition analysis and electrochemical properties test, the influence of surface micro-electric field on the strength of saline soil induced by soluble salt ion is discussed, and the comparative analyses is made with soft soil from Nansha, China. The results of test and analysis show that the cause of formation, soluble salt content and surface charge density are the important reasons for the different strength characteristics between them, and also the main factors for coastal saline soil from Kuwait characterized by low strength and low Atterberg limits. The research on strength characteristics of coastal saline soil may provide experimental parameters and theoretical basis for the treatment of saline soil foundation in this project and valuable references for foundation treatment in other coastal saline soil areas.