In order to discuss the efficient cultivation technique of low-quality and low-effect secondary forest of Hainan Province, lay the foundation for the renovation of the low-quality and low-effect secondary forest of Hainan. The undergrowth vegetation diversity, biomass and its soil physical and chemical properties of inferiority and inefficient Pinus caribaea Morelet secondary forest in state forest Tongshi farm (109o31′E, 18o46′N) in HaiNan Province were researched, and the correlation between them was studied by the method of quadrats investigation and sampling analysis. The results showed that the plant richness and diversity indices of shrub layer were higher than the herb layer, but the evenness index was lower than the herb layer; the general result of undergrowth vegetation biomass was that shrub layer was more than grass layer. The content of soil total N was between 1.15-1.78 g/kg, where there were significant differences in the content of total N among in the 0-20 cm soil, 20-40 cm soil and 40-60 cm soil. It was showed significant differences in the content of available P between the 40-60 cm soil and the other two. It was showed significant differences in the content of quick K between the 0-20 cm soil and the other two. From the experiment results, it was concluded that the soil nutrient was poor. The diversity indices of undergrowth species had significant positive correlation relationship with the content of soil total N, P, K and quick K, but no obvious correlation relationship with the bulk density, pH value, and little correlation with soil physical and chemical properties.