The method is proposed to detect human body with frequency modulation continuous wave (FMCW) and millimeter-wave (mmWave) radar. Human detection is the first step before performing vital sign monitoring, which is one of the most important applications for mmWave radar. In this Abstract, we exploit the range profile (RP) variation within a certain distance to detect human. This requires less computational storage spaces than conventional approaches. First, we perform clutter removal processing to weak ranging signals, and then calculate the standard deviation of each chirp to identify whether there is human in radar’s field of view (Fov). The experimental results confirmed that the accuracy our proposed method is higher than 97% even if the received ranging signals are weak.