An integrated 2mm band sub-harmonic mixer based on quartz circuits was presented. General harmonic mixer theory was introduced. The equivalent circuit model for the anti-pair diodes was built. Then the extensive simulation and optimization by the full wave analysis software were done. When the 59GHz LO signal’s power was set between 7~14dBm, the mixer yielded a least conversion loss of 17dB and a maximum loss less than 20dB under working frequency of 116~120GHz. The P1dB of the mixer is about 1dBm. The isolation between the three ports is better than 20dB.The measured results of the sub-harmonic mixer are agreed well with the simulated ones.