Abstract: The ozone uptake characteristics of poplar under natural conditions in different dominance hierarchies were studied based on sap flow methods. The results showed that: the diurnal variation of ozone concentration was of single peak type, with the value ranging between 25.5 and 175.0μg/m3; the tendency of its variation was consistent with that of temperature; the diurnal variations of the ozone uptake rate (F_o_3) and canopy ozone conductance (G_o_3) in different tree shape levels were of unimodal type; the change of F_o_3 followed an order of depressed tree (43.24nmol/(m2·s)) > middle tree (29.77nmol/(m2·s)) > dominant tree (24.56nmol/(m2·s)), while the value of G_o_3 ranked as the dominant tree (101.59mmol/(m2·s)) > depressed tree (92.92mmol/(m2·s)) > middle tree (81.60mmol/(m2·s)). The mean value of F_o_3 was (32.52±7.87) nmol/(m2·s), while that of G_o_3 was (92.04±8.18) mmol/(m2·s) in different tree shape levels. The effects of Rs, VPD and t on G_o_3 and F_o_3 were in an order of dominant tree > depressed tree > middle tree. Peak concentrations of ozone lagged behind the peak value of sap flow density, and over-high ozone concentration would inhibit transpiration. There was a good consistency between the changes of atmospheric ozone concentration and sap flow density, and sap flow technique is suitable for the calculation of ozone uptake of plants.