The invention discloses a broadband matching method used for a power amplifier, a construction method and the power amplifier. The broadband matching method is based on a circuit structure of a multi-resonant cell, and has a characteristic of being symmetric in horizontal and longitudinal structures. The broadband matching method is constructed by the method of vertical construction of the multi-resonant cell. An input matching network or an output matching network of the power amplifier is the broadband matching network. The broadband matching network and the power amplifier provided by the invention have the advantages of being miniaturized, high efficient and wide in frequency band.