The invention discloses a heat treatment method for an ultracrystalline
magnetic core. The method comprises the following steps of: annealing in a non-
magnetic field mode during the heat treatment of the ultracrystalline
magnetic core, and protecting by using
argon, namely setting different annealing temperatures under the condition of a certain annealing heat-preserving time t, testing at the nine temperatures of 520 DEG C, 530 DEG C, 540 DEG C, 550 DEG C, 560 DEG C, 570 DEG C, 580 DEG C, 590 DEG C and 600 DEG C, comparing test results, and finding the optimum annealing temperature T; setting the heat-preserving time under the condition of a certain optimum annealing temperature T, testing within 15 minutes, 30 minutes, 45 minutes and 60 minutes, comparing test results under different kinds of heat-preserving time, and finding the optimum heat-preserving time t; and drawing a conclusion, wherein the optimum annealing temperature is between 560 and 570 DEG C, and the optimum heat-preserving time is 60 minutes. The heat treatment method is simple, the performance of the
magnetic core subjected to the heat treatment is high, and property parameters of the ultracrystalline magnetic core are far higher than standard parameters, so the properties of products with the magnetic core can be improved greatly, and the cost of the products can be reduced.