Hollow self-cooled millstone and cooling method

The invention relates to a hollow self-cooled millstone. The middle part of the millstone is of a hollow structure; a cooling water pipeline penetrates through the hollow structure. The utilization rate of cooling water is improved, the service life of the cooling water pipeline is prolonged, and self cooling of the millstone is realized. The inner side of a millstone surface is set to be an arc concave surface, and an arc concave surface baffle plate is arranged on the outer side of a millstone head, so that after being injected, the cooling water is enabled to be reflected to the millstone, and under the action of centrifugal force, effective cooling of cooling water is guaranteed. A telescopic transparent organic glass cover is arranged above the millstone, the working state of the millstone can be seen, and a short circuit phenomenon of an instrument and injury to workers, which are caused by splashing of water, can also be avoided. The cover can be extended and retracted in the rotation shaft direction of a motor, so that a sample can be conveniently placed or taken out by a tester.