Abrasive water jet cutting (AWJ) technology has an important application prospect in emergency repair of oil depot. A new type of rear-mixed AWJ nozzle was studied in this paper, and the multiphase flow characteristics in nozzle were analyzed by numerical simulation. The results show that the negative pressure is generated inside the nozzle. As the water moves towards the downstream of the nozzle, the rigidity of the water decreases, which is beneficial to the entry of abrasives.The turbulent kinetic energy is mainly distributed in the contraction section. In order to improve the mixture of water and abrasive, it is recommended that the abrasive inlet be close to the contraction section as close as possible. At the nozzle outlet, the abrasive is mainly distributed near the wall, while the water is concentrated near the axis, and the water and the abrasives mixed unevenly at the nozzle outlet.The wear of nozzle mainly occursat the downstream of the contraction section and upstream of the cylinder section. Although the new rear-mixed AWJ nozzle cannot completely solve the issue of uneven mixture of water and abrasive, the distribution of the abrasive inside the nozzle is more symmetrical and the nozzle wear is relatively uniform, which reduces the inhomogeneity of the abrasive and water and prolongs the service life of the nozzle to a certain extent.