Aimed at the problem ofmetal target detection, a metal target detection method based on millimeter-wave radiometer imaging is proposed, according to the millimeter-wave radiometric characteristics of metal. Firstly, the method utilizesmillimeter-wave radiometer to scan target and image. Secondly, the image is labeled with region labeling algorithm. Thirdly, the fake target information is excluded through analyzing the area of labeled regions, and the metal target is then detected . Experimental results show that the method can detectmetal target effectively from various background, therefore, it provides a base for later target recognition, tracking and location.