To improve continuous supply ability of present pre-mixed abrasive water jet (AWJ) system, a new method is proposed to realize continuous feeding using the principle of jet pump suction and mixed abrasive. Entrainment of abrasive in pump mixing chamber is attributed to negative pressure field formed by ejection of a certain speed pressurized water from the jet pump nozzle. Abrasive mingled with water in chamber flows through throat pipe and diffusion pipe into high pressure hose, and transforms into required AWJ by acceleration of cutting nozzle. Based on analysis of structure and working principle, structure and size are designed for this continuous feeding system. Numerical simulation method is used to optimize the design of the area ratio of cutting nozzle and jet pump nozzle, which influences continuous feed and jet performance. Area ratio impact on system performance and optimal value range are analyzed and determined, respectively. System performance is verified by laboratory pressure test, continuous sand and cutting experiments. The result indicates that negative pressure and sufficient pressure gradient formed at abrasive inlet under suitable area ratio structure are beneficial for absorption and acceleration process, besides, the front of cutting nozzle still retain enough static pressure that can be converted into kinetic energy to facilitate efficient continuous operation of premixed abrasive water jet system.