Abstract: A possibility study was conducted for controlling the degradation of productivity of Chinese Fir plantations by the help of its undergrowth. The results were as follows:1. The undergrowth develops quickly in Chinese Fir stands of closure 0.7. Its biomass and nutrient can accumulate 4~5 t/ha and 80~100 kg/ha respectively in 4~5 years and approximately 10~15 t/ha of organic matter can be obtained during a rotation by slash cutting tending.2. The content of nutrient in undergrowth is higher than that in trees. The undergrowth contributes more to nutrient cycling in the near-mature and mature stands.3. The undergrowth is favorable for the increase of the soil organic matter and soil nutrient content, especially available nutrient content.The results showed that it is possible to control the degradation of Chinese Fir plantations by the help of undergrowth and ecological management and self-fertilization of forest.