Abstract: Chestnut forest is an important economic forest species，widely distributes in the south of Liaoning province. The most part of chestnut forest is artificial pure forest with single stand structure and low vegetation coverage in Anji county of Zhejiang province. In the article，16-year-old chestnut woodland in Hanggai town of Anji was selected， ten kinds of plants including Torreya grandis，Photinia × fraseri and Illicium henryi were planted inter the forest， plant spacing of 5 m×5 m，seedling height was 1-3 m，with chestnut of the same area as control，the effects of stard transform on species diversity under forest were studies. After 3 years，sample plot was investigated. The results showed that regeneration layer was the major component of plant species diversity，in tree and shrub layer，species richness was 17.13（ ± 2.64），Shannon-Wiener index was 2.45（± 0.29），Simpson index was 0.87（± 0.06），all higher than the corresponding unimproved land value（13.5 ± 1.93，2.23 ± 0.16 and 0.86 ± 0.03）. The species richness and diversity index showed no significant difference between transform stands and primary chestnut forest，while transform forest community structure tended to be more stable than primary forest.