The profile morphology,main physico-chemical properties and clay mineral composition of acid brown soil,grey brown soil are disscussed according to the natural conditions of the mountain soil formation in the west Hubei.The results show that both of the acid brown soil and grey brown soil belong to the forest soils formed in the middle and upper parts of subalpine and medium mountain areas in the subtropic climatic zone under cold and humid conditions.But their physico-chemical properties differed obviously with the same soil types in the northern China.The acid brown soils are distributed in the middle and upper parts of the medium altitude mountains,with an altitude higher than the dark yellow-brown soils,being the forest soils with the vegetations of bright conifer and broadleaf deciuous scrubs.Their distribution altitude is higher in the southwest Hubei than in the Northwest Hubei.Grey brown soil is the forest soil formed under colder and more humid conditions than the acid brown soil and located at a higher altitute than the acid brown soil about 2500m above the sea level in Shen nongjia region,and its vegetations are dark conifer forests.