A human-body foreign-matter detection method and system based on millimeter-wave image. The method comprises: obtaining a millimeter-wave grayscale image of a human body; extracting a human-body contour image in the millimeter-wave grayscale image; constructing a vertical space distribution histogram in a vertical direction and a horizontal space distribution histogram in a horizontal direction for the human-body contour image; obtaining positions of limbs of the human body according to the vertical space distribution histogram, the horizontal space distribution histogram and a pre-set human-body proportion model; identifying a foreign matter in the human-body contour image according to pre-set foreign-matter feature identification models; and marking a position of the foreign matter on the human-body contour image according to the positions of the limbs, and generating a foreign-matter detection result.