The invention discloses an active design method of a machine tool parameter and an interval change range thereof. The active design method comprises the following steps: expressing the changes of a dynamic joint part rigidity parameter and an equivalent moving quality and damping parameter of a machine tool system by interval numbers; calculating the sensibility interval of a machine tool structure parameter; estimating the inherent frequency change range of the machine tool; presetting vibration mode and distribution expected by a system; then, according the vibration mode and distribution expected by the system, adopting an interval mathematics operational method to summarize the active design of the machine tool parameter into the solving of a global optimization problem of a target function; and solving the global optimization problem of the target function to determine the change range of the system parameter. The active design method can solve to obtain the change interval of the machine tool system parameter under the interval parameter.