Abstract: Water potential at turgor loss point(Ψ_tlp)and relative water content at turgor loss point(C_RW,tlp)have been considered important measurements of the drought tolerance of trees. This study compared Ψ_tlp and C_RW,tlp by two types of P-V curves(typeⅠ: Ψ versus C^-1_RW; typeⅡ:Ψ^-1 versus 1-C_RW)and with three common calculation methods(mathematical method, graphical method, and PV computer program)in type Ⅱ for major tree species in the eastern mountain region of Northeast China. The results showed that average values of Ψ_tlp and C_RW,tlp of eight species calculated from type Ⅰ were 0.20 MPa and 3.17% higher than those calculated from type Ⅱ. Especially parameters for the coniferous species Larix gmelinii and Pinus koraiensis were more significantly affected by two types of transformations than those of the broad-leaved species. In addition, the difference among species changed with different types of transformations. Ψ_tlp and C_RW,tlp calculated by three methods for the same species were similar except that Ψ_tlp for Ulmus japonica calculated by the computer program was significantly higher than the value calculated by the mathematical method(P<0.05). The determination coefficients(R²)between values of Ψ_tlp or C_RW,tlp calculated by the three methods were in the range of 0.63-0.90(P<0.01), and the values of R² of the mathematical method and graphical method were the highest. Compared with the typeⅠcurve, the shape of typeⅡ P-V curve had the advantages of being smooth and the obvious boundary between the curve part and the straight portion, making the turgor loss point easily detectable via plots of the data. Meanwhile, the graphical method had the advantage of easily applied, which can make it being used widely in the future.