A low power 245 GHz subharmonic receiver for gas spectroscopy sensor application has been proposed. The receiver is characterized by low power, high linearity and high integration level. The receiver consists of a four stage common base （CB） LNA, a 2^nd passive APDP （anti-parallel diode pair） SHM （subharmonic mixer）, a 120 GHz push-push VCO with 1/64 divider, a 120 GHz PA （power amplifier） and an IF （intermediate frequency） amplifier. The receiver is fabricated in a SiGe:C BiCMOS technology with f_T/f_max=300/500 GHz. The measured conversion gain is 10.6 dB at 245 GHz with 3-dB bandwidths of 13 GHz , noise figure is 20 dB, and simulated input referred 1 dB compression point is -9 dBm. The receiver dissipates a power of 99.6 mW without 120 GHz VCO-PA chain, and a power of 312 mW with the 120 GHz VCO-PA chain.