When human’s body been injured. The value of length and area of wound, rotation angle range of joint are the important references for forensic judge. This paper presents a Polygon-Division method to measure human body surface wound area. This method based on the photo image of wound region and with computer aided. For experiment, I design and implement a software program. The result of experiment reached the demand of precision of forensic judge. The program based this method is more simple to operate and more efficient than other programs, and this is a practical and simple method to measure human body surface wounded area.