The reasonable arrangement of the main shaft rolling bearing of the gantry milling machine, the configuration form of the two-support main shaft bearing, the configuration form of the two-support main shaft bearing, including the selection, combination and arrangement of the main shaft bearing. Mainly according to the requirements of the designed spindle components in terms of speed, load-bearing capacity, rigidity and accuracy. The commonly used two-support main shaft rolling bearing arrangement form is given. The following general principles should be followed when determining the configuration of the two-support spindle bearing: 　　1) The requirements of the planer and milling machine to adapt to the rigidity and load-bearing capacity should first meet the required rigidity and load-bearing capacity. When the radial load is large, the bearing configuration can be selected; when the radial load is small, the configuration can be selected. In addition, double-row bearings are more rigid than single-row bearings. Since increasing the rigidity of the front support can effectively increase the rigidity of the main shaft components, the bearings that increase the rigidity should be arranged on the front support.　　2) The maximum speed allowed by the planer and milling machine to adapt to the speed requirements of different models, specifications and accuracy grades of bearings is different. Under the same conditions, the point contact is higher than the line contact; the cylindrical roller is higher than the tapered roller. Therefore, it is necessary to comprehensively consider the requirements of the rigidity and speed of the spindle components to select the bearing configuration form.　　3) The planer and milling machine adapts to the accuracy requirements of the spindle components to bear the axial seven thrust bearing configuration directly affects the axial position accuracy of the spindle. The working performance and application range of the three commonly used configurations. When the front end is positioned, the main shaft is heated and deformed and extends backwards, which does not affect the machining accuracy, but the front support structure is complicated, it is inconvenient to adjust the bearing clearance, and the front support heats up a lot. The characteristics of the back-end positioning are opposite to the above. When the two ends are positioned, the axial clearance of the bearing changes greatly when the main shaft is heated and elongated.