Abstract: To analyze the spatial structure of Cunninghamia lanceolata non-commercial forest, the plantation predominanted by the 24-year-old C. lanceolata located in Fushou Forest Farm of Yueyang City, Hunan Province of central China was taken as the study object, and four structural parameters, i. e. mingling degree, neighborhood comparison, aggregation index and storey index, were calculated based on the Voronoi diagram that can determine the reference tree爷s neighborhood groups of trees. The results showed that: 1) there were nine kinds of different sizes of spatial structure unit in this community, and the most common phenomenon was that the reference tree had five close neighboring trees; 2) the average mingling degree of stand was 0.23, indicating the simple spatial allocation and poor mixing of different tree species; 3) the distribution of neighborhood comparison based on DBH changed with a fluctuant pattern, and the stability of species in the arborous layer was good;4) the average aggregation index of stand was 1.01. The individuals of tree presented the succession trend from aggregated distribution to random distribution; 5) the average storey index of stand was 0.23, and the spatial configuration was relatively simple in the vertical space.