The invention belongs to the technical field of integrated circuit manufacturing, and particularly relates to a microwave-assisted atomic layer deposition method and reactor. The atomic layer deposition reactor comprises a reaction chamber, a microwave source, a vacuum pump and gas pipelines, wherein the top of the reaction chamber is provided with a quartz window, a substrate tray is arranged inside the reaction chamber, the side wall of the reaction chamber is provided with a magnet exciting coil, the microwave source is arranged above the quartz window, the vacuum pump is used for adjustingthe vacuum degree of the reaction chamber, the gas pipelines comprise a first reaction source gas conveying pipeline, a second reaction source gas conveying pipeline and an inert gas pipeline which are used for conveying a first reaction source, a second reaction source and inert gas respectively, the microwave source carries out microwave irradiation decomposition on the first reaction source, the microwave source and the magnet exciting coil jointly generate a microwave electron cyclotron resonance source, and the second reaction source is excited to form high-energy plasmas. According to the microwave-assisted atomic layer deposition method and reactor, the conductivity and ductility of a thin film can be effectively improved, an ideal step coverage rate and the accurate thin film thickness control capability are achieved, and the requirements of an advanced CMOS integrated circuit process can be met.