An annular clean metal casting mold has a mold body which includes a cold bottom mold plate and a peripheral cold mold plate in connection with the cold bottom mold plate. An annular hot preservation layer is disposed inside the peripheral cold mold plate. A cyclic clean crystalline region is formed between the peripheral cold mold plate and the annular hot preservation layer. A sacrificial crystalline region is formed inside the cyclic hot preservation layer. As the outer race of the annular clean crystallization zone contacts large area of the peripheral low cold mold plate, releasing heat rapidly, while the inner race contacts the annular hot preservation layer 3, heat dissipation is extremely slow, naturally result in forming orientational crystallization. The vast majority of impurities and segregations in the liquid metal are gathered at the portion contacting with the annular hot preservation layer, and thus after the liquid metal is solidified, the gathered impurities and segregations can be removed easily, to obtain a clean casting ingot.