Transpiration conductance model is an important resistance model to measure water vapor output at the canopy atmosphere interface. Our study foucused on its characteristics and response to environmental factors, which provided a theoretical basis for clarifying the water vapor output mechanism at the canopy atmosphere interface. In this paper, Platycladus orientalis forest observation station of forest ecosystem in the capital circle was taken as the research object. Through analyzing the dynamic changes of canopy conductance and aerodynamics conductance by TDP thermoprobe, we measured the density of sap flow in the trunk of Platycladus orientalis forest and monitoring the main environmental factors such as photosynthetic effective radiation, saturated water vapor pressure difference, air temperature, and wind speed. And the model of canopy-atmospheric transpiration conductance was derived and calculated so as to build a simulation, which clarified the response of canopy atmospheric transpiration conductance to various environmental factors. The results showed that the trend of transpiration conductance in non-growing season was consistent with that in canopy; the growing season was consistent with the trend of aerodynamic conductance, and the trend was single peak throughout the year. The difference between transpiration conductance and canopy conductance in winter remained stable (around 45 mol m^-2 s^-1);the maximum difference value among transpiration conductance, canopy conductance and aerodynamic conductance in other seasons was at the peak level of canopy conductance and aerodynamic conductance; the annual average transpiration conductance was the largest in winter (86.92 mol m^-2 s^-1) and it was smaller and stable in other seasons (40-50 mol m^-2 s^-1); in the non-growing season, the effect of environmental factors on transpiration conductance was basically the same as that on canopy conductance, and temperature was the most important factor (r=-0.198) while other environmental factors had little impact (r<0.1); in the growing season, wind speed was the most important factor (r=0.488); the influence of photosynthetic effective radiation (r=0.228) and vapor pressure deficit (r=-0.299) was significantly increased, and the influence of temperature was reduced (r=0.114). The model of transpiration conductance simulated the change rule of Platycladus orientalis transpiration in different seasons, clarified the influence mechanism of environmental factors, canopy conductance and aerodynamic conductance on transpiration conductance, and confirmed that we should pay attention to the influence of aerodynamic conductance on transpiration in growing season.