Abstract: Hand dorsal vein display device has been invented in recent years,but because the hand dorsal vein images have lower contrast degrees,so for,this equipment is still not very precise for the extraction of blood vessels.For this problem,this paper presents a new vein extraction method,which complete the extraction of vein with improved histogram equalization algorithm and NiBlack segmentation method.Through simulation,compared with contrast limited adaptive histogram equalization algorithm (CLAHE),the segmentation effect has made some improvement.