Abstract: This paper deals with the influence of capillary water on the strength and deformation of soils, and on the seepage flow state of levees and dams. Silty soils possess both higher water head and higher permeability, water pressure transmitting rapidly. So that the influence of capillary water in the engineering with silty soils is obvious. The principal research results are: ①According to the comparison tests of unconfined compression strength with samples immersed in the water or not, and with theoretical analysis, it has been demonstrated the capillary water head results the further consolidation and strength increasing of the soil. The strength increasing values of the tests are the same as the values of theoretical calculation. ②Analyzing and calculating the decreasing process of capillary water tension accompanied by soil expansion in silty surface strata on heavy rain condition. ③Using electric analog test and sand model test, the influence of capillary water on the seepage flow state of levees and dams is studied. The capillary water results the increasing of the seepage flow quantity and the height of release point. ④Two new empirical formulae of capillary water head and permeability coefficient of sand and silty soils are presented. The research results can be applied to the engineering of foundation foundation pits, levees and dams with silty soils.

Key words: capillary water, silty soils, strength, consolidation, seepage