以机床结构固有频率变化范围可控为目的，提出一种机床参数及其变化范围的主动设计方法，实现了系统结构参数允许变化范围的快速计算。首先，将动结合部刚度参数变化以区间数表达，给出了机床结构参数敏感性区间的计算方法以及准确预估固有频率变化范围的计算方法;然后，根据预先给定系统期望的振动模态及分布，采用区间数学运算法则将机床参数的主动设计最终归结为求取目标函数的全局优化问题，确定了系统结构参数的允许变化范围;最后，通过一个两轴耦合进给系统验证了所提出方法的可行性。

：Prediction of machine dynamics at the design stage is a challenge due to the time-varying configuration,the axis coupling forces and the lack of adequate methods for handling the nonlinearities change of joints. A active design method is proposed for the purpose of the change controlled of CNC machine natural frequency: the nonlinear rigidity parameters of joints are expressed by the interval parameters,and an interval sensitivity method is presented to calculate the machine tool parameter; an accurate calculation method for prediction the change interval of the dynamic properties is set up,which provide a better understanding of the system dynamics; according to the desired vibration mode and their distribution of given system,an interval algorithm and the global optimization algorithm are introduced in the design process and used to determine the allowable variation range of some critical stiffness parameters. Two cases study are conducted to verify the reliability and effectiveness.