The characteristics of moisture retention of main soils in Shanghai area have been studied by tension plate method (0-1 bars) and pressure membrane method (1-15 bars). Results showed that:In general, soil water suction was conversely correlated with soil water content. Under the low water suction, the soil water-holding capacity was dependent mainly on the content of organic matter, the adsorption of organic colloids and the influence of soil structure;while under the high water suction, it was closely related to the soil texture (i.e. the content of clay) and the molecular attractive force of specific surface area as well as the adsorption of organic colloids.