Abstract: Based on the synchronous measurements of the trunk sap flow by GREENSPAN sap flow system, and the variation of meteorological factors measured by HOBO automatic weather station apparatus, the correlations between the meteorological factors and dynamic variation of trunk sap flow of Magnolia denudata trees under different weather conditions were studied. The results indicated that solar radiation was the decisive factor that influenced the trunk sap flow, while temperature and relative humidity were the leading factors influencing the trunk sap flow. The regression model for evaluating the correlations between the trunk sap flow and the meteorological parameters was established through multi-linearity regression analysis. The differences between the calculated values and the measured values could be calculated by the regression model to study the extent of water shortage inside the M. denudata trees in the course of transplanting.