Abstract: The full ceramic bearings are of great significance for the accuracy retention of the electric spindle. However, due to the differences in material properties between ceramic bearings and steel shafts, dynamic changes in the mating state between the bearing inner ring and the shaft are caused by thermal deformation during high-speed operation, thereby affecting the motion characteristics of the spindle. To address this issue, a thermal-induced deformation model for the electric spindle with full ceramic bearings is proposed. In this model, the effects of rotational speed and interference fit on the mating state of the bearing inner ring and the circumferential stress are taken into account. The research results indicate that the interference fit of the inner ring of the all-ceramic bearing should be smaller than that of the metal bearing. This study is considered to have important theoretical and practical significance for the robust design of electric spindles equipped with full ceramic bearings.