The invention discloses a waste magnesium recovery device, including a melting system, a casting ladle system, and a bar molding system. An efficient vacuum induction heating furnace is used to melt,and melting time is reduced. A bottom column type discharge hole is used in the casting ladle system, and discharge is convenient and fast. A crystallizer assembly can directly pour recovery liquid into magnesium bars. The device helps a magnesium alloy section processing enterprise remove a step that magnesium ingots melt to form magnesium alloy bars, and effectively reduces production cost and production efficiency.