The current millimeter-wave radar has a poor detection effect and small detection range when applied to detect multi-person vital signs. In view of these problems, a method for extracting and separating multi-person heart rate and respiration is proposed. First, Capon beam forming technology is used to form null for signals in non-target areas, and phase extraction and phase unwrapping operations are carried out for target areas. Secondly, an adaptive harmonic tracking algorithm is used to filter noise. Finally, the variational mode decomposition method improved by particle swarm optimization and sample entropy (PSO-SE-VMD) is used to decompose the signal to obtain modal components, select appropriate modal components, and extract heart rate and respiration through a short-term autocorrelation algorithm. The experimental results show that the mean square error of heart rate is 5.55 and 3.15 when the included angle is 30° and 60°, respectively, which realizes multi-person detection and effectively improves the detection range.