A power-adjustable RF (radio frequency) output circuit is disclosed, which includes a RF frequency source transformer, wherein: one output end of the RF frequency source transformer is connected with a gate of a power amplifier module, another output end of the RF frequency source transformer is connected with a gate bias voltage control circuit; a source of the power amplifier module is connected with ground; the gate of the power amplifier module is connected with a resistor which is connected with ground, a drain of the power amplifier module is connected with a fixed voltage DC (direct current) power supply and also connected with a RF filtering network for outputting a RF power through the RF filtering network.