A method for measuring divergence angle of pulsed laser beam is proposed based on dual-frame image fusion and charge coupled device (CCD) characteristic that CCD camera response to illumination is nearly linearity in a certain range. The feasibility and accuracy are proved by experiment and mathematical simulation via Matlab. This method expands the application scope of illuminance measured and makes up the defects that CCD dynamic response range is not wide, and is a good solution to the question that pulsed laser beam divergent angle measurement accuracy is not high. The experimental results show that measurement accuracy of this method is 2%.