An injection locked magnetron microwave generator with a recycle of spurious energy, relating to a microwave power source, includes a frequency selective reflector for recycling the spurious energy of a magnetron and satisfies locking requirements of an output frequency of a high-output-power magnetron with a low-power injection signal. The microwave generator includes n magnetrons and n locking devices, n≧1. The locking devices inject locking signals into the corresponding magnetrons. The n locking devices are connected with a microwave source. Output terminals of the magnetrons are connected with corresponding frequency selective reflectors for reflecting the spurious microwave signals outputted by the magnetrons back to the magnetrons. The microwave generator, with a simple structure, effectively recycles the spurious energy outputted by the magnetrons, and reduces the power of the injection signal and costs of the microwave source and the overall microwave generator.