The invention discloses a supercharging device in magnesium-based material continuous casting and extruding equipment. The supercharging device is arranged so that the effective friction force can beestablished in a magnesium-based material during the continuous casting and extruding process. The supercharging device structurally comprises a casting and extruding roller and a casting and extruding shoe seat which cooperate with each other, a casting and extruding groove is formed in the roller surface of the casting and extruding roller, a supercharging bearing bush cooperating with the casting and extruding groove is arranged on the corresponding side face of a casting and extruding shoe, the inner side surface of the surcharging bearing bush is arc-shaped and coats the roller surface ofthe casting and extruding roller, the arc radius R of the inner side surface is 0.8-1.2 mm larger than the arc radius r of the roller surface of the casting and extruding roller, furthermore, the contact area between the inner side surface of the supercharging bearing bush and the casting and extruding groove of the casting and extruding roller adopts a radial progressive structure, the unfoldinglength L of the contact area is the length of the arc corresponding to the radian angle alpha of the supercharging bearing bush, and the inner side surface of the supercharging bearing bush is divided into three areas (a platform area, a small-angle slope area and a large-angle slope area) from top to bottom. The supercharging device can be widely applied to various continuous casting and extruding equipment of magnesium or a magnesium alloy.