The horizontal grinding method of CNC external cylindrical grinding machine. When the horizontal grinding method is used to grind the outer circle, the width of the grinding wheel is larger than the grinding width of the workpiece. The workpiece does not need to make longitudinal (workpiece axial) feed motion. Intermittently move along the transverse feed to realize the radial feed fr of the workpiece until the grinding reaches the size requirement. Its characteristics are: give full play to the cutting ability of the grinding wheel, high grinding efficiency, and also suitable for forming grinding. However, the large contact area between the grinding wheel and the workpiece during the grinding process increases the grinding force and the workpiece is prone to deformation and burns. In addition, the shape error of the grinding wheel directly affects the geometric accuracy of the workpiece, the grinding accuracy is low, and the surface roughness value is large. Therefore, a high-power, high-rigidity grinder must be used, and sufficient cutting fluid must be given to achieve the purpose of cooling while grinding. Using the horizontal grinding method requires that the process system has good rigidity, and the workpiece should be short rather than long. This kind of grinding method is usually used for the fine grinding process of the short stepped shaft journal.