It is essential to accurately measure the laser beam divergence angle, which determines the scope of detection of laser fuze. The character of the laser beam emitted from the laser fuze was described. Besides, according to the propagation characteristics of Gaussian laser through a lens, the laser beam divergence measurement can follow the measurement of the laser beam diameter in the focal plane of a lens. Moreover, several key parts in the test of laser beam diameter which affect the accuracy of the results were presented in detail, such as the determination of CCD integration area, background map subtraction. The measurement results and their uncertainty indicate the measurement methods are reliable and accurate.