The invention provides an impedance matching system and method. The system provided by the invention comprises an impedance matcher which is connected with a continuous wave radio frequency power supply and a reaction cavity, and is used for automatically carrying out the impedance matching of the output impedance of the continuous wave radio frequency power supply and the input impedance of the reaction cavity; a selection switch and a load circuit, wherein the selection switch is used for enabling the continuous wave radio frequency power supply to be selectively connected with the reaction cavity or the load circuit; and a control unit which is used for controlling the selection switch to switch to be connected with the reaction cavity or the load circuit according to a preset time sequence, so as to convert continuous wave output of the radio frequency power supply into pulse output through the impedance matcher, and load the pulse output to the reaction cavity. According to the invention, the system does not need an expensive radio frequency power supply with a pulse mode function, thereby reducing the cost. The system can enable the impedance matcher to carry out the automatic impedance matching in a pulse mode, and effectively improve the instable and non-repeated matching in the pulse mode.