Abstract: Based on the activities of International Association of Hydrological Science on the XXI General Assembly of International Union of Geodesy and Geophysics,advances and tendencies of hydrological study since 1990 are delineated from such four aspects as hydrological observation,hydrological processes,hydrological modelling and hydrolo gical characteristics.Scientists have paid more and more attentions to the measurement of soil moisture and ground water quality.With the studyonl and surface parameterization,the research of the middle stages of rain-fall-runoff processes will be strenthened.Scale,sustainability,uncertainty and predictability are still hot topics of hydrology.