The invention relates to a metal die capable of testing the flowability of casting nonferrous alloys. The metal die mainly comprises an upper metal die and a lower metal die, wherein the upper metal die comprises a left half die and a right half die and connected with the slide track of the lower metal die through insert block guide rails; buffer block insert blocks are arranged between the left half die and the right half die; a sample ejection plug block is arranged below the sprue base of the lower metal die. Molten metal flows through the buffer block insert blocks through a sprue cup, then flows to a sprue and the sprue base after being subjected to speed control by buffer holes, and finally flows into a helical line-shaped cavity and form a helical sample. A heating through hole and temperature measuring through holes are formed in the metal die, so that the metal die can be heated by a heating rod and the temperature of the metal die can be measured through a thermocouple, so as to facilitate testing on the flowability of the nonferrous alloys under different temperature conditions. The test objects of the metal die are magnesium, aluminum and other nonferrous alloys. The metal die has the advantages of simple structure, easy operation and obvious test effects, and can be used for testing the flowability of the nonferrous alloys under the conditions of temperature control and speed control.