[Objective] The aim of this study is to provide the theoretical basis for optimizing the stand spatial structure and for developing its ecological, economic and cultural functions by analyzing and evaluating the stand spatial structure of Cunninghamia lanceolata ecological forest.[Method] Neighbor trees of the object one was determined based on the Voronoi diagram, and Stand spatial structure index was calculated based on the measured data in eighteen permanent sample plots and the retest data in nine permanent sample plots of Cunninghamia lanceolata ecological forest of different age groups(young, half-mature and near mature)in Fushou Forest Farm of Hunan province. Mingling index, neighborhood comparison, uniform angle index, competition index, stand layer index and open degree of stand were selected to analyze their spatial structure characteristics before and after thinning and replanting. Meanwhile, adopted multiplication division method making a multi-objective programming for each spatial structure parameter, the evaluation index of stand spatial structure was put forward. Making reference to target and technical index of near-natural transformation of plantation and using the integration of qualitative and quantitative methods, the evaluation index values of stand spatial structure were divided into five grades.[Result] Before thinning and replanting, stand layer index and mingling index was generally low, indicating that mingling degree of tree species was low, the stability of the stand vertical space structure was weak, and the use of vertical space of trees was underutilized. Also, neighborhood comparison of DBH of the stands was closed to moderate state, the numbers of trees in diameter classes were distributed uniformly, and there was minor difference between individual trees, uniform angle index of the stands was belonging to the intermediate state of uniform and random distribution, which was not ideal horizontal distribution pattern of the stands. The open degree of young forest was high, but that of half-mature and near mature forest was low, indicating that growth space of young forest was sufficient, but half-mature and near mature was lack of growth space. As Cunninghamia lanceolata grown and developed, the competition index of stands showed an increasing trend,indicating that the competition pressure among individual trees was gradually increasing with the growth of tree age. The evaluation index of stand spatial structure of Cunninghamia lanceolata ecological forest of eighteen permanent sample plots was 0.185 9-0.364 7, belonging to the evaluation grade 1 and 2 accounting for 11% and 89% of the total sample plots respectively, without the sample plots belonging to the grade 3, 4 and 5, illustrating that the spatial structure of Cunninghamia lanceolata ecological forest was far from ideal spatial structure, and need to optimize the stand spatial structure. However, after thinning and replanting, the stand layer index and mingling index were increased significantly, the degree of difference among individual trees became apparent, and the growth space of juvenile and medium became more sufficient. The evaluation index of the stand spatial structure of Cunninghamia lanceolata ecological forest of nine retest sample plots was 0.346 2-0.613 1, belonging to level 2, 3 and 4 of evaluation grade accounting for 11%, 78% and 11% of the total retest sample plots respectively, which illustrated that the spatial structure of Cunninghamia lanceolata ecological forest of different age groups was improved obviously.[Conclusion] There were unreasonable factors in the stand spatial structure characteristics could be found by analyzing the stand spatial structure, which provided basis for management measures to optimize the spatial structure. The evaluation index of stand spatial structure was put forward, it explored a new approach to the ideal spatial structure of Cunninghamia lanceolata ecological forest and provided the theoretical basis for the evolution of the ecological forest improving mainly Cunninghamia lanceolata plantation toward ideal structure. According to the evaluation results of spatial structure of Cunninghamia lanceolata ecological forest in the research area, it was objectively reflected the actual situation of its spatial structure before and after thinning and replanting.