A novel carbon nanotube field effect transistor with double stepwise doping channel (DSD-CNTFET) is presented for improving the device performance including short-channel effects (SCEs). DSD-CNTFET structure includes two stepwise doping which are broadened throughout the channel. The doping concentration of DSD-CNTFET channel is at maximum level at drain/source side and is reduced stepwise toward zero at the middle of channel. Simulation results show that this structure on CNTFET enhances the device performance. In comparison with graded double halo structure with equal saturation current, the proposed DSD-CNTFET structure shows the improved leakage current and on/off current ratio.