Abstract: Based on the data observed in successive years，the dynamic effects and its parame-ters in a Chinese fir plantation catchment was studied by aerodynamic principles．The re-sults could be presented as follows：the length of zero plane displacement is 9.52—9.95m，the canopy roughness 2.32—2.53m,the mixed length of the upper canopy sur-face 0.274m，the coefficiency of leaf resistance 0.367，the wind delay factor in the canopy 1.98,and the turbulanee force and friction velocity decrease as the depth of the canopy increase．Dynamic parameters have significant correlation with the velocity of airstream which is strongly effected by temperature layer sum and forest structural charaeteris-tics．Owing to the delay of airflow by leave and branches in the canopy，the turbulance and its spread characteristics above the upper canopy are quite different from that within the canopy．In the catchment，heat vapour of the canopy and gravity play an important role in the formation and development of the turbulance stream．

Key words: Chinese fir plantation, Dynamics effects, Parameter, Temperature layer sum, Turbulance stream