The present invention provides a crystallizer and a vertical hollow round billet continuous casting machine, including an outer crystallizer and an inner crystallizer, the outer crystallizer having a容纳空腔, the inner crystallizer being of a cylindrical structure, the inner crystallizer being sleeved in the outer crystallizer, the inner crystallizer being able to rotate relative to the outer crystallizer, and the side wall of the inner crystallizer being provided with a lubricating oil hole for introducing rapeseed oil to play a heat transfer and lubricating role. The beneficial effect of the present invention is that by injecting rapeseed oil through the lubricating oil hole on the inner crystallizer, the rapeseed oil can be carbonized under the action of the hot billet, filling the gap between the billet shell and the inner crystallizer, playing a heat transfer and lubricating role, and at the same time, the inner crystallizer has a rotating function, and the carbon layer formed with the rapeseed oil is very conducive to demoulding and cooling, so that it can effectively prevent the hollow billet from sticking to the inner crystallizer.