The main contents of the cooling system of the laser welding machine include checking the water quality of the cooling water, cleaning the water tank and the pipeline, and checking whether the action of the protection circuit is normal or not. In the use of frequent cases, once a week to check the water quality of a laser welding machine , in order to ensure the quality of the cooling medium at any time. Check method is to use a multimeter resistance profile in 2MW, the metal exposed part of two probe measurement terminal with 1cm interval distance parallel to the insertion of a cooling water, the resistance readings should be at least more than 250kW. If the reading is below this value, the cooling water should be replaced immediately. Check the work can be carried out when changing water. Laser welding machine cooling system in normal operation or not, determine whether the safe operation of the machine, otherwise it may lead to the problem of safety equipment equipment of the electro-optic conversion efficiency is low, the laser spot, laser scintillation and equipment overheating, and a series of laser rod breakage.