On the basis of studying the beam characteristics of high power diode laser (HPLD), variable beam divergence design method for high power diode laser is presented. A variable beam divergence shaping system with two plane-convex cylindrical lenses perpendicular to each other for extended astigmatic source is designed. This system can obtain the required beam divergence and change it in a certain range by defocusing. A mathematical model between motion quantity and beam divergence is set up. The results simulated by commercial optical design software show that this system can reduce the beam divergence and change it continually in a certain range. The transformed beam can illuminate different area objects.