Abstract: In this paper,the approaches and methods for determining directly or indirectly parameters of hydrologic models are investigated by using remote sensing images. Based on the parameters extracted from Landsat TM images,the daily monthly and annual runoffs in the Caoe River Basin were simulated through the Sacramento hydrological model with considerable accuracy. Thus,this technique provides a potential way for dynamic simulation and monitoring of hydrological processes in the area without observed hydrologic data.