Abstract: Based on stepped-frequency continuous wave (SFCW) and MTD filter with joint detection in time and frequency domain, a new method for life detection is proposed to get the range information in detecting human beings. Firstly, stepped-frequency continuous echo model in life detection built is according to human vibration model. Secondly, range gate is divided and time domain detection is used to gain the actually range gate where the targets are. And thirdly, the frequency information of these range gates is obtained, and then the effect of statistic objects elimilated through MID filter. At last, frequency domain detection is applied to get human beings targets. The theoretical validity is illustrated by simulation results.