The invention relates to a final stage three-way power combining amplifying circuit applied to power amplifier of a mobile communications base station system. The circuit includes at least a first power divider, a power combiner, a Doherty amplifier and a Class AB amplifier, as well as some transmission lines and phase-shift lines. A first output port of the first power divider is connected to a first input port of the power combiner via a first phase-shift line and the Doherty amplifier by concatenating them with transmission lines. A second output port of the first power divider is connected to an input terminal of a Class AB amplifier via a transmission line, an output terminal of the Class AB amplifier is connected to a second input port of the power combiner via a microstrip line, and the output terminal of the power combiner outputs an amplified radio frequency signal. The invention can meet the requirements of both high efficiency and low cost. Meanwhile, the reliability and stability of the power amplifying circuit are also ensured.