It is difficult to realize the active control of block segmented primary mirror for splicing technique. The model is established based on the active control system of segmented primary mirror. The single-input single-output systems are obtained after the diagonalization of transfer function matrix of a multi-input multi-output system using the static decoupling. And the simplified control system model is designed. On this basis, the controller design of the control system is completed. We set up an experimental system of segmented mirror in the laboratory with four hexagonal mirrors to implement the active control technology. Three actuators control the tip and tilt error of each sub-mirror. The results show that the correction time of unit tilt error is 2.6 s. According to the power spectral density analysis of the tip of sub-mirror, the correction bandwidth of dynamic tilt error reaches 0.34 Hz. The efficient fast correction of static splicing error and the real-time effective correction of dynamic error are realized.