Abstract: The characteristics of ancient tree resources were investigated and evaluated to provide the decision basis of ancient tree protection in the plain area of the middle and upper reaches of the Anning river. A total of 826 ancient trees were investigated, belonging to 22 species, 21 genera and 5 families. The results showed that the main tree species were Pistacia chinensis, Platycladus orientalis, Ficus virens var. sublanceolata, Gleditsia sinensis, Quercus acutissima and Celtis sinensis(n>50). C. sinensis population was in best health, F. virens var. sublanceolata, G. sinensis and Quercus acutissima populations were secondary, Pi. chinensis and Pl. orientalis were the worst, these six tree species were the excellent native tree species as well. The two correlation coefficients of tree height, trunk girth and crown width were the highest in Pi. chinensis samples, which fitted the regression curve of tree characteristics, but the characteristic correlation of C. sinensis samples were not in significant correlation.