The simplified mathematical model was established for DWJ2030_〖KG-*2〗FB water jet machine tool of semiclosed loop control of suspensionarm type, as the analysis object made by one company. The influence of moment of inertia ratio, backlash clearance, and stiffness to mechanical transmission part on running performance was simulated with analysis, and the analysis results were certificated in test by using Yaskawa SigmaWin+ software and Renishaw laser interferometer. The simulation and testing results show that it is good for improving the systems dynamic response and stability by reducing moment of inertia ratio of feed axis, and moment of inertia ratio close to or less than 1 is preferably. Backlash clearance of ball screw is one of the factors that reduces positioning accuracy of machine tools and generates contour error. The compensation by using a laser interferometer can reduce the impact of backlash clearance effectively. Also increasing the stiffness of transmission mechanism is in favor of improving the system's response, positioning accuracy and stability. However, it can hardly improve system's performance when stiffness reaches to a certain value.