Spindle unit with various journal bearings is increasingly adopted in numerous machine tools. Due to overlooking the interaction between spindle and bearings in analysis and optimization leads to a less accuracy for simulating real work codition. In order to overcome this shortage, a practical coordination optimization strategy is perposed. Taking both bearing and spindle as subsystems of the overall system, using coordinator to account the interaction. Equivalent stiffness is adopted to ensure the analysis accuracy and save the computation time. An optimum design example is presented.