The high frequency communication, also known as shortwave communication system, works in the frequency band of 2.000 0 to 29.999 9 MHz. In the design of software such as communication mode and data processing, HF communication system is at the forefront of scientific and technological development like other communication subsystems. However, there are few studies on hardware design, especially antenna design and impedance matching, especially on shortwave communication technology applied to civil aircraft. However, in order to achieve the maximum power transmission to the load and to improve the noise figure, it is important to change the impedance. Therefore, this paper first introduces the equipment composition of the HF communication system，then focuses on the impedance matching process of the system and the internal circuit composition of the antenna tuner, and then focuses on the working principle and design ideas of impedance matching, aiming to provide a reference for the index improvement of the HF communication system.