Half-wavelength AC transmission (HWACT) requires that the electrical length between the sending and receiving ends is about one half of a power frequency wavelength. If the electrical length is shorter than one half of the fundamental frequency wavelength, appropriate technology should be employed to compensate the electrical length in order to maintain the HWACT characteristics. In order to overcome various drawbacks of the existing passive tuning, this paper proposes a π type flexible tuning, including two parallel tuners and one series tuner. Then based on their main circuit topologies and their working principle, their control strategy is designed for the half wavelength flexible tuning, and the simulation results confirm that the proposed π type flexible tuning is feasible. With the appropriate control strategy, the flexible tuning device can realize the additional function of power factor compensation, and the simulation results show that with the implementation of the power factor compensation function, the reactive power will not pass through the half wavelength AC transmission line, as a consequence the fluctuation amplitude of voltage and current along the half wavelength line will be reduced.