The invention provides a radio-frequency power amplifier system for a microwave wireless power transmission device. The radio-frequency power amplifier system comprises a first-stage power amplification circuit, a second-stage power amplification circuit and a third-stage power amplification circuit, which are sequentially connected in series; the first-stage power amplification circuit mainly comprises a signal-source-level power amplifier of an indium gallium phosphide heterojunction two-stage transistor; the second-stage power amplification circuit mainly comprises a driving-stage amplifierof a gallium arsenide heterojunction two-stage transistor; and a third-stage power amplifier mainly comprises a gallium nitride high-electron-mobility transistor. The radio-frequency power amplifiersystem provided by the invention is simple in topological structure, low in component cost, good in heat dissipation performance and low in temperature rising; high-power output can be carried out stably; and thus, power, efficiency and stability requirements of the microwave wireless power transmission device can be satisfied.