Since atomizing nozzle is easily subject to erosive wear during preparation of magnetic abrasive in atomization method, the work aims to solve the difficulty in forming effective flow field, analyze erosive wear mechanism of atomizing nozzle, and provide theoretical basis for design of atomizing nozzle. Al2O3 hard abrasive particles and SiC nozzle were selected, theoretical analysis and computer simulation (CFD) were combined to explore erosive wear mechanism, and atomization pressure was selected to simulate its relationship with maximum erosive wear rate. Based upon theoretical analysis, it was concluded that the erosive wear forms of the atomizing nozzle were brittle fracture and micro-cutting. Based upon CFD computer simulation analysis, both erosive wear distribution diagram of the atomizing nozzle, and the rule that erosive wear rate increased with the increase of atomization pressure were obtained. At the atomization pressure of 3 MPa, the maximum erosion wear rate of atomizing nozzle reached 5.3×10-7 kg/(m2?s). At the atomization pressure of 5 MPa, the maximum erosion wear rate reached 1.3×10-6 kg/(m2?s), 59% higher than that at 3 MPa. A method of separating the hard abrasive injection and atomization process is proposed to improve structure of the atomizing nozzle, so as to reduce erosive wear of the hard abrasive particles on inner wall of the atomizing nozzle during preparation of the magnetic abrasive.