To better evaluate the quality and safety of reinforced concrete structures used in power transmission and transformation, a corrosion detection method was proposed for reinforced concrete structures in power transmission and transformation based on the microwave transmission method. The accelerated corrosion test of steel bars was carried out, and reinforced concrete models with different corrosion degrees were obtained. A microwave detection test platform was built. The variation of the amplitude and phase of the transmission coefficient S21 was analyzed through microwave nondestructive testing of reinforced concrete models with different degrees of corrosion. The results show that the accelerated corrosion test in a wet salt sand environment can obtain steel bars with different corrosion degrees in a short time. When the lift-off distance is 4 mm, the corrosion state of steel bars in concrete can be effectively identified by the amplitude and phase change trend of transmission coefficient S21. The research can provide a reference for corrosion detection of power transmission and transformation-reinforced concrete structures.