The water-reserving benefits of man-made forest and natural secondary forest in the upper reaches of Miyunreservoir were systematically studied through determining the physical properties and infiltration of the soil

moistureholding capacity of forest litter and through observing the surface runoff produced by simulated rainfall. The resultsshow that each species of these trees has distinct benefits of water-reserving. The water-reserving benefits of naturalsecondary forest are higher than that of man-made forest. Using curve-fitting techniques

the relationship between thevelocity and time of soil infiltration and between the time and amount of that were given respectively. The runoff coef-ficient model of forest soil under simulated rainfall was developed with step by step regression.