Permanent sample plots were laid under forests in the area of 3045-3125N.lat.and 10252-10324E long.with the altitude of 1200-4300 m above sea level in the Wolong Natural Reserve.Sample plots were set up on 5 mountain forest soils,i.e mountain yellow soils under the evergreen forest,mountain brown forest soils under the deciduous and broad-leaved forest,moumain dark brown forest soils under the coniferous deciduous and broadleaved mixed forest,mountain brown dark coniferous forest soils under the pue fir forest,and alpine meadow soils under the alpine meadow.Observation began in 1981 and ended in 1984.Structural patterns,total biomass (11.24-113.94 t/ha),chemical and physical prbperties,elemental content of the forest floor were studied.Finally,the function of forest floor on wate conservation,nutrient supply,promoting biological respratory intensity and soil development are discussed.