Abstract: To solve the technical bottleneck problem of slow footage and rapid wear rate of milling tools for workover under complex wellbore conditions, the early recommended slope milling tool for workover was taken as the research object based on previous research. First of all, a mechanical analysis model of the abrasive grain based on the shear slip line theory model was established, and the quantitative relationship between abrasive grain angle and working torque of the milling tool was clarified. Then a single abrasive grain cutting simulation software based on the secondary development of ABAQUS in Python language was developed, and the parametric modeling of single abrasive grain cutting simulation model was realized. Besides, the milling tool for workover with single abrasive grain of different angles was developed and the cutting experimental tests were completed. At last, the preferred angle of the abrasive grain was determined from five aspects including angle type, chip formation process, chip morphology, cut scar morphology and work characteristics. The results show that the cutting force of the abrasive grain with zero angle has the fastest growth rate, the value of the abrasive grain with positive angle is the largest, and the value the abrasive grain with negative angle is the smallest with a smoothly fluctuating in the range of 642.5-785.3 N. With the increase of the angle of the abrasive grain from 0° to 45°, the chip volume gradually decreases, the chip length decreases from 5 mm to 2 mm, and the chip shape changes from roll-like type to irregular granular type. When the angle of the abrasive grain is 5° and 10°, the cut depth of the workpiece surface is the largest that reaching 1.0 mm. When the angle of the abrasive grain is 8°, the material removal mass is the largest that reaching 9.49 g, and the working torque is only 28.7 N ·m, which shows the working process is relatively smooth. Considering the working efficiency as well as working safety, the preferred angle of the abrasive grain on the slope milling tool for workover is -8°.