Abstract: Based on the data of threedimensional ultrasonic anemometer on the 30 m of micrometeorological tower at secondary oak forest of Xiashu in period of 2008.03—2009.02, zero plane displacement d and roughness length Z0 were calculated with temperature variance method(TVM) and the impact factors such as wind direction, wind velocity, friction velocity and leaf area index LAI were analyzed. The results showed that both the zeroplane displacement d and the roughness length Z0 both obviously increased and then decreased as the crown leaves growth and then defoliated. The average d and Z0 were 15.20 m and 1.86 m in growing season and 14.25 m and 1.24 m in nongrowing season. d did not change a lot in different wind directions, while Z0 obviously changed in two main wind direction 90°—180° and 300°—30° with average Z0 value 1.23 m and 1.81 m respectively. Z0 decreased with increasing wind velocity or increased with increasing friction velocity, while it changed a little when wind velocity increased to a certain value. d and Z0 both increased with increasing LAI, while Z0 had a small change when LAI increased to a certain value. According to the effective data ratio, it was appropriate that the coefficients of TVM C3evaluated 3.5 and C1 evaluated 0.9 to 1.05.