Abstract: An algorithm of PID controller parameters identification based on the fastest model was presented to tune PID controller parameters for an inertial feature system. With input and output data of the inertial feature system, this method identifies the first-order characteristic system by the least square method (LSM) firstly, then identifies the second-order fastest model of the inertial feature system according to the demands of the first-order characteristic system, control signal, the stable and dynamic properties of the inertial feature system, and then the PID controller parameters were calculated synchronously. Simulation results show that the algorithm makes the PID controller have the characteristic of the fastest response and provides an effective method for calculating the PID controller parameters.