Traditional algorithms of hand vein image segmentation are insensitive to image detail and have poor segmentation effect. A new improvement method based on threshold image was put forward. The key of this new method is iterative calculations instead of calculating the mean of every plate. It divides the image into several parts, and each part uses an optimal threshold scheme to get a threshold image. Its size is the same with the original vein image. Then the partial information can be enhanced through binary processing of the image. The simulation experiment showed that the proposed method is effective.