In order to improve power quality, a scheme of compensating reactive power is proposed in this paper. Firstly, the basic principle of voltage regulation is introduced. After making comparison with several control methods, thyristor controlled reactor (TCR) compensator is selected due to its certain feasibility and stability. Besides, the improving control strategy is performed based on the least mean square (LMS) algorithm, which makes it vital in accelerating convergence rate and enhancing control accuracy. At last, a 500kV extra high voltage and 300km long -distance transmission line model is built with 12-pulse connection structure of TCR. The Matlab simulation results verify the theoretical analysis and provide with super advantages in accelerating dynamic response.