Hydraulic architecture parameters of 5-year-old saplings of Pinus tabulaeformis and Platycladus orientalis under drought stress were measured using the improved flushing method. The hydraulic architecture of trees is based on differences in the hydraulic properties of the xylem and is characterized by two important functional aspects, hydraulic safety and hydraulic efficiency. The hydraulic efficiency is proportional to the specific conductivity (Ks) of the xylem, while the hydraulic safety describes the resistance of the xylem against embolism formation, which quantized through the percent loss of conductivity (PLC). The aims were to study the compromises between hydraulic safety and hydraulic efficiency and adaptations by determining the hydraulic architecture parameters changed with drought stress of P. tabulaeformis and P. orientalis, which have different leaf types and ecological strategies, and to search the mechanism influenced the trade-offs. The results showed that PLC increased and Ks decreased in all the ramification and stem segments with increasing drought stress. The water potential thresholds were -0.55, -0.49, -0.43 MPa for P. tabulaeformis and -0.90, -0.78, -0.74 MPa for P. orientalis respectively, in the three categories of branches 0, 1 and 2. As the water thresholds increased, embolisms vulnerability was highest in branch 2, followed by branch 1 and branch 0 in both species, and higher in P. tabulaeformis than that in P. orientalis. This may relate to the number of water transportation tissues in different branches or the ability of resistance to the embolism. PLC increased and Ks decreased in non-restrict area stem segment, visa versa in the restrict area. As the PLC reached the maximum, the water potential were -5.08, -4.62, -4.07 and -6.79, -6.40, -6.21 MPa respectively in the three different branches. Therefore, the ecological strategy of P. tabulaeformis and P. orientalis were as much as possible to serve the trunk or lower ramification branch in this phase. The vulnerability was higher in non-restrict area stem segment than in restrict area stem segment. P. tabulaeformis showed higher vulnerability than P. orientalis, may be relate to the number or diameter of the tracheid and less possibility to cavitation in restrict area stem segment. Under drought stress, P. tabulaeformis and P. orientalis showed different strategies to adapt to the embolism caused by the decreased water potential with relative ramification in different area stem segment. The strategies included: (1) keeping higher hydraulic security, such as the lowest PLC reduction of P. tabulaeformis and P. orientalis under light drought mean higher hydraulic safety; (2) decreasing hydraulic security to tradeoff the hydraulic efficiency, i.e. branch 2 of P. orientalis had highest Ks reduction and lowest PLC reduction under heavy drought, which represented higher hydraulic and lower hydraulic efficiency than other branches; and (3) decreasing hydraulic safety and hydraulic efficiency to level at which tree growth is not restricted. That occurred in the branch 0 of P. tabulaeformis under serious drought, showed that both hydraulic safety and hydraulic efficiency were decreased.