Abstract: In order to explore the effects of plant species richness and interspecific interaction on plants and the community productivity,the growth of Dalbergia obtusifolia,Cajanus cajan,Dalbergia balansae and the community biomass with different species number and species combination was investigated.The results were as follows:the effects of species richness and interspecific interactions on plant growth varied largely.D.obtusifolia had the highest biomass in a single plantation, the biomass decreased by the increasing species richness,it grew slowly when planted with other plant species.The biomass of C. cajan was highest when the species richness was two and showed the best grow with D. balansae.The growth of D. balansae was affected by neither species richness nor interspecific interaction.The total biomass of community showed a single peak curve under a certain planting density, the biomass of the community reached the highest when the species richness was two.The study showed that with lower plant density,the growth and community productivity of woody plants are affected by species richness and species interactions but different plant species vary a lot. In the process of establishing lac plantations,it is not suggested to mix D. obtusifolia with other species in density plantation, while a rational mixed planting of C. cajan and D. balansae is beneficial to the growth of host plants and could improve the productivity of lac plantation.