Characteristics of tongue pose the most important information for tongue diagnosis. So far, extensive studies have been made on extracting tongue surface features. Meanwhile, the sublingual vein diagnosis, one important part of tongue diagnosis, has received increasing attention. In this paper, a novel image acquisition device specially designed for capturing sublingual vein images is introduced. Different from existing tongue image acquisition devices, monochrome industrial CCD with enhanced near infrared sensitivity is used under near infrared light source. Corresponding segmentation method of sublingual veins for the captured near infrared sublingual images is proposed subsequently. Experimental results reveal that the proposed method did indeed segment the sublingual veins from the near infrared sublingual images with an acceptable degree of accuracy.