The invention provides a method and a device for preparing porous blister steels through foaming of fused masses. The method comprises the following steps: firstly, a foaming agent is flatly laid at the bottom of a crucible and covered with a stainless steel mesh, so as to prevent the foaming agent from floating upward; secondly, the crucible is placed into a heating furnace for heating until thetemperature is 50 to 100 DEG C lower than the temperature that the foaming agent begins to discompose, and molten steels are poured into the crucible; thirdly, a heat-insulated heating device is utilized to adjust the temperature of the molten steels in the crucible until the temperature is 250 to 350 DEG C above the temperature that the foaming agent begins to discompose; and fourthly, after heat preserved stirring for 1 to 2 minutes, the crucible is taken out and air-cooled to the room temperature, and the porous blister steel materials are obtained. The method and the device can increase the residence time of the molten steels within a temperature region for decomposing the foaming agent, prevent the foaming agent from floating upward, and improve the structural characteristics and thedistribution characteristics of holes of prepared samples, has simple technique, is easy to operate, and is an ideal method for preparing the porous blister steels.