Abstract: Active transpiration is an important metabolic basis for the rapid growth of bamboo, and plays a key role in maintaining the ecosystem water cycle and water balance in forested areas. How to accurately estimate the transpired water of bamboo forest is a pressing methodological problem needed to be solved. At present, thermal dissipation sap flow measuring system (TDP) is widely used in the research of tree water physiology and forest hydrology, but less applied in bamboo forest. A few studies on the bamboo transpiration measured with TDP were reported, but the results were unconvincing, because of the lack of rigorous experimental verification of the method. The authors considered that the non-uniform thermal distribution caused by the structural heterogeneity of bamboo wall and by the large hallow in the culm center could be the major reason for the inaccuracy of the measurement of bamboo transpiration by using TDP which works based on the heat flux exchange principle. In this paper, an approach combining water-injection induced hydraulic pressure and sap flow changing device together with whole-plant container weighing method was suggested to verify the applicability of TDP in estimating bamboo water use. Considering the bamboo’s population structure and the lack of secondary growth in bamboo wall, it was proposed that bamboo performed a cross-culm compensation for hydraulic limitation in way of water allocation through rhizomatous interconnection, and bamboo transpiration was mainly affected by culm age rather than by culm form and size. Therefore, to analyze the age effect on bamboo transpiration and to investigate the water use patterns of bamboo forests with different planting densities could provide references for the effective stand design and related implementing measures for bamboo forest production and catchment water resource management.