An automatic liquid supply device for 
magnesium alloy cast rolling comprises a cast rolling 
machine, a front liquid box, a heat preservation holding furnace, a 
melting furnace and a 
magnesium ingot conveying device. The front liquid box is used for storing 
magnesium liquid, and an outlet of the front liquid box is communicated with a 
casting mouth of the cast rolling 
machine. An outlet of the heat preservation holding furnace is communicated with an inlet of the front liquid box. The 
melting furnace and the heat preservation holding furnace are communicated through an automatic 
siphon. The magnesium 
ingot conveying device is used for conveying magnesium ingots to the 
melting furnace. According to the automatic liquid supply device for 
magnesium alloy cast rolling, the magnesium ingots are conveyed to the melting furnace by the magnesium 
ingot conveying device, the magnesium liquid sequentially passes through the melting furnace, the heat preservation holding furnace and the front liquid box to enter the cast rolling 
machine, the whole process is continuous and stable, the quality of a cast-rolled plate is improved, the labor intensity of workers is lowered, and production efficiency is improved; and real-time liquid supply control can be carried out over the melting furnace, the heat preservation holding furnace and the front liquid box, continuous liquid supply is achieved, and production efficiency, 
continuous production stability and production safety are improved.