The utility model discloses a device is smelted to magnesium alloy, it includes smelting furnace, gas protection device, gas -supply pipe, intake pipe and controller, the smelting furnace includes furnace body, crucible, heater, temperature sensor, annular blast pipe and weeping detector, the furnace body includes first diapire and extends the first side wall of formation perpendicularly along first diapire, the crucible includes the second diapire, follows the second lateral wall that the second diapire is buckled and is extended, forming first clearance between first diapire and the second diapire, forming the second clearance between the first side wall and the second lateral wall, first clearance is linked together with the second clearance, the weeping detector is fixed on first diapire, is located be connected in the first clearance and with the controller electricity, the annular blast pipe holds in the second clearance, is linked together and encircles the crucible setting with the gas -supply pipe, temperature sensor installs and is connected on the second lateral wall and with the controller electricity, the heater is located the furnace body and is connected with the controller electricity.