Abstract: The paper studies on the characters of organization of forest communities in Guangdong. The diversity and ecological dominance as well as community evenness of twenty two forest communities in Guangdong are measured on the basis of Shannon-Wiener index and Simpson index as well as evenness formula. The results show that three indexes have an effect on explaining the organization level of forest community. The species diversity index of subtropical evergreen broadleaved forest is about 4—5, the ecological dominance is about 0.08—0.12, the community evenness is about 0.7—0.8. According to the further research of the measured results, the relationships between three indexes and the meaning of three indexes in community study as well as the application of three indexes in foresty practice are discussed