In order to prevent and remedy soil degredation of Chinese fir plantation, This paper discusses the following issues: increasing stand light intensity, decreasing canopy closure, developing undergrowth, ameliorating soil properties and enhance soil biological activity through thinning. Research results show that while canopy closure is less than 0 7, undergrowth vegetation can grow fast. Biomass have 4～5 t per hectare after thinning 4～5 years. It is obvious to enhance nutrient contents and amount of three ...