In order to solve the problem that the current beam quality analyzer can only be used to evaluate the beam quality of small caliber and low power lasers, an experimental study on the attenuation and compression technique of high power laser beam quality measurement was carried out. A device for measuring wave aberration and beam quality of the compressed beam laser was built, and an experiment was carried out to determine the influence of the assembly error on beam quality. The experimental results show that, with the increase of the field of view, the measurement deviation of M² of 1/3 compressed beam assembly at 1.2° field of view is less than 5%. A polarization splitting device was built, and the influence of attenuated components on beam stability was studied. The experimental results show that the stability of the quasi-single mode laser with random polarization is more susceptible to the depolarization of the attenuated components than that of the multi-mode laser. A high power laser beam quality measuring device with high reflection type and wedge-plate type was built to measure the beam quality of 1 kW quasi-single mode laser. The experimental results show that in the high reflection measuring device, the depolarization occurs when the beam passes through the high reflector, which leads to a smaller beam quality measurement result, and the results of the wedge-plate measuring device can more accurately reflect the beam quality.