We assess future climate change impacts on stratosphere-troposphere exchange (STE) and their influences on tropospheric O3, using a chemistry coupled climate model. Tropospheric O3 distribution and budget were predicted decadally for 1990 to 2100 with emission changes (for O3 precursors) and climate change specified by the IPCC SRES-A2 scenario. Our simulations show increases in stratospheric O3 transport to the troposphere as a result of enhancement in the tropospheric and stratospheric circulation with climate change in the model. With emission changes only, net stratospheric O3 input to the troposphere was simulated to decrease by ~20% during 1990--2100, but to increase by ~80% with including climate change also. Simulated increases in net cross-tropopause O3 transport are most significant particularly after 2050.