In this article the skewness of sap flow pattern and the time lag between stem sap flow and canopy transpiration in Acacia mangium, Schima superba and Bambusa chungii which were characterized with different hydraulic structures were analyzed. The spatial variation in sap flow within tree trunk and its effect on transpiration were also investigated. The results showed that both skewness and time lag in S. superba decreased with the increment of stem diameter at breast height (DBH). However, similar changes in A. maingum were not significant because of open canopy of the stand and differentiation among individuals. The skewness of sap flow pattern in B. chungii increased with DBH, but no significant relation between time lag and DBH was observed because of its smaller canopy that evenly received radiation. However the time lag in B. chungii was smaller than in S. superba with similar DBH. Re-allocation of sap flow within stem during water transport implied that hydraulic conductivity was an important factor affecting time lag. The spatial heterogeneity of canopy transpiration was related to water storage. Larger tree had relative more water storage and therefore lower heterogeneity. In smaller trees that normally had less water storage, sap flow was preferentially allocated to the east and south branches where more sunlight was received than in the other directions, which leaded to higher heterogeneity in canopy transpiration. Being restricted by soil moisture during dry season, the water storage in larger trees contributed more contribution to transpiration than in wet season. In contrast, contribution of water storage to transpiration in smaller trees was less in dry season than in wet season, since the transpiration was more restricted by the quantity of stored water. Being radiated earlier or later and the intensity of radiation on canopy may have caused differences in time pattern of sap flow and its azimuthal difference in tree stem. However, the transversal exchange of sap flow attenuated this difference and among-trees difference concealed the azimuthal difference of sap flow. The skewness ratio (the ratio value between sknewness of sap flow at clear bore height and that at breast height) of tree with smaller DBH was higher in wet season than in dry season, but it was reverse for the trees with larger DBH. Generally the skewness ratio decreased with the increase in DBH.