Thyristor Controlled Interphase Power Controller (TCIPC) has certain effects to control the flow of power system and improve the transmission capacity of transmission line. On the basis of researching the TCIPC basic principle, this paper analyzed the controlling characteristics of the link transmission power with TCIPC which were impacted by the inductor and capacitor branch. The mechanism analysis of TCIPC to improve the stability of the system were also carried out. The nonlinear power system containing tuning TCIPC was made linearization to construct a pseudo linear system by adopting the inverse system method. And the linear quadratic regulator (LQR) optimal control theory has been utilized to this system to design the TCIPC nonlinear controller. The simplified model of a single machine infinite bus system with tuned TCIPC was built to emulate. The simulation results show that the control strategy designed by inverse system method has a good performance and can improve transient stability of power system when the big interference happened in the system.