Abstract: A millimeter-wave non-contact radar sensor for human respiration and heartbeat rate detection is presented in this paper. The sensor works in 120 GHz band and uses frequency modulation continuous wave system (FMCW) scheme. The hardware architecture consists of an integrated RF front-end, a digital phase-locked loop, an intermediate frequency (IF) preprocessing circuit, and a control processor. Algorithm softwares such as waveform control, IF data acquisition, and signal processing are executed by an embedded control unit. The IF preprocessing circuit integrates the functions of sensitivity frequency control (SFC) and automatic gain control (AGC), therefore the sensor′s capability to detect targets with different scattering intensities and at different distances can be improved. A prototype is fabricated and measured based on design results, the experimental results show that within a 1.5 m range, the measurement accuracy of the heartbeat rate is over 93.52%, and the measurement accuracy of the respiratory rate is over 93.33%.