Method and system for measuring spot diameter of laser

The invention discloses a method and a system for measuring the spot diameter of laser. The method comprises the following steps of: reflecting incident light of a laser light source by using a collimating device, enabling the reflected light to pass through a through hole of a diaphragm device, checking the diffraction effect of the reflected light passing through the through hole by using a spot analyzer, adjusting the collimating device, and collimating the light path of the laser. Removing the light spot analyzer, installing a power meter at the position of the light spot analyzer, measuring the power of reflected light of the laser light source passing through the through hole by using the power meter, and recording the power as first power; measuring the power of reflected light of the laser light source after the diaphragm device is removed by using a power meter, and recording the power as second power; and substituting the radius of the through hole of the diaphragm device, the first power and the se