Objective The segmentation of medical infrared image plays an important role in large-scale infrared image processing.In order to obtain the human body information quickly and effectively，this paper presents a method of segmenting and extracting human body regions in medical infrared images.Methods Infrared thermal imager collects infrared images of a naked person in a quiet room.The whole region of the human body is obtained by the threshold method.The threshold is obtained by analysis of the gray level distribution of medical infrared image，and the human body regions are segmented by the feature points of the human body which are extracted by the human body horizontal distance(width)function combined with the special direction bright band in the infrared image.Results There are 64 of 72 images from 8 persons divided by the method without bias.It proves that the method can segment and extract the human body regions from infrared images with human body in upright posture.Conclusions This segmentation algorithm for infrared image of human body can provide a technical basis for disease screening and computer-aided diagnosis based on infrared images.