Hollow hair roller

A hollow hair curling cylinder comprises a cylinder body, a first sealing cover and a second sealing cover, the first sealing cover and the second sealing cover are connected to the two opposite ends of the cylinder body respectively, the center of the first sealing cover and the center of the second sealing cover are each provided with a through hole, and the through holes of the first sealing cover and the second sealing cover are connected with each other and connected with the interior of the cylinder body; a containing groove is formed in the inner wall of the barrel and protrudes towards the center of the barrel, and the front end and the rear end of the containing groove extend to the edge of an opening of the barrel respectively. According to the hair dryer, hair is wound on the outer side of the winding drum, an external power source is connected through the internal heating block, the heating block emits heat after being powered on, the containing groove is fixedly attached to the cylinder body, and