The results has identified tree species biodiversity indexes in IIA, lIB, IlIA1 forest states in Linh Thong commune, Dinh Hoa district, Thai Nguyen province which are calculated by Simpson's index, information theory, Shannon-Wearve link function in 9 typical standard plot, in which all standard plots were investigated and collected indicators such as tree species, a number of peak trees and a number of regenerants. Calculated results have identified a rich diversity of species and the consistency of the high number of individuals. In which, the peak trees biodiversity is determined by the Simpson's index (D, D ') for the value D' = 0.96427 - 0.969867 higher than D = 0.961425 - 0.966864 on all forest states, by the formulas D' adjusted for the chosen sample size. For regenerated trees species, the regenerants are abundant and most crowded in the IlIA1 forest state and the consistency among individuals in the same species is the highest, compared to IIA, lIB forest states.