To achieve efficient AlGaN-based Deep Ultraviolet Light-Emitting Diode (DUV LED), the N-polar LED structure with grading quantum barriers is proposed to manipulate the carrier transport. By adopting the N-polar structure, the hole injection and the electron overflow issues can be improved due to the reversed polarization-induced potential barrier for carrier transport in p-type electron blocking layer. Furthermore, the impacts of different grading directions and schemes on the device performance are investigated. Simulation results show that grading the Al composition linearly from 0.65 to 0.6 for the 12 nm-thick AlGaN quantum barriers along the (000-1) can well balance the quantum barrier height and slope, thus resulting in remarkable improvement of hole injection as well as 53.6% enhancement of optical output power. The proposed design provides a straightforward and effective solution to the electron overflow and hole injection issues, which shows promise in the pursuit of higher efficiency DUV LED.