A novel expert hydro/aero-static spindle design system strategy is presented in this paper. It is based on the comprehensive principles of machine design, machining dynamics and metal cutting mechanics. The transmission and lubrication types of the spindle are decided by a selection system, which utilize a dedicated logical choice algorithm in the light of the specifications of both workpiece material and desired cutting condition. Hydro/aero-static spindles are designed by this system from its dynamics perspective. The chatter vibration of the spindle is automatically improved by optimizing the structural parameters of the spindle. Meanwhile, the predicted Frequency Response Function (FRF) of the spindle based on the rotor dynamics is integrated to the chatter vibration stability law. Consequently, the expert design system enables the structure of machine tools to be designed efficiently with a higher precision. The proposed system was demonstrated through an aerostatic spindle design for micro-array structures machining. (C) 2013 Elsevier Ltd. All rights reserved.