The invention discloses a method and a device for preparing synthetic gas or hydrogen with BGL pressuring slag gasification and pure oxygen non-catalytic partial oxidation. The method comprises the following steps: directly sending crude gas at an outlet of a BGL furnace into a pure oxygen non-catalytic partial oxidation furnace and combusting with the preheated pure oxygen, forming high temperature gas and then sending to prepare qualified synthetic gas or hydrogen. According to the invention, the high temperature combustion of partial oxidation furnace is conversed to useful ingredients or simple substances which are easy to be removed and processed. Such as methane and light oil are conversed to useful medium hydrogen and carbon monoxide; thiophene is conversed to hydrogen sulfide and the like. The invention also discloses a device for preparing synthetic gas or hydrogen with BGL pressuring slag gasification and pure oxygen non-catalytic partial oxidation.