Metal grain refining method

The invention discloses a metal grain refining method. The method comprises the following steps: simultaneously pouring a first metal melt and a second metal melt; and enabling a pouring fluid of the first metal melt and a pouring fluid of the second metal melt to be converged and mixed in the pouring process to form a third metal melt. According to the method, two mother alloy liquids with different components and temperatures are simultaneously poured at a certain speed by utilizing a left-right pouring ladle, are converged in the air and flow into a tundish to obtain a uniformly mixed target alloy, and then the target alloy is poured into a casting mold for solidification forming. The method has the advantages that after the melts of the left casting ladle and the right casting ladle are simultaneously poured into the tundish, the mixed melt is more uniform in components and temperature on the macro level, but more and finer small molten pools with non-uniform components and temperatures are formed on the