The utility model relates to the technology of frequency conversion, in particular to a millimeter wave signal generator. The utility model discloses a millimeter wave frequency source which utilizes frequency mixing technology to convert frequency and output millimeter waves to overcome the defects of high phase noise and severe near-end spurious degradation of a millimeter wave frequency source in the prior art. The technical scheme includes that the millimeter wave frequency source is characterized by comprising an oscillator and a frequency mixer, a first frequency branch and a second frequency branch, wherein input ends of the first frequency branch and the second frequency branch are respectively connected with the oscillator, output ends of the first frequency branch and the second frequency branch are connected with the frequency mixer, the output end of the frequency mixer is an output end of the millimeter wave frequency source, and the output end of the frequency mixer is connected with a filter. The millimeter wave frequency source is applied to a millimeter wave system, frequency converters as followed and the like, and is capable of reducing same phase noise, decreasing near-end spurious degradation and improving system performance.