The invention provides a high-strength magnetic core and a preparation method thereof, and relates to the technical field of magnetic core production. The magnetic core comprises, by weight, 50-54 parts of ferric oxide, 18-22 parts of copper oxide, 12-16 parts of zinc oxide, 6-10 parts of nickel oxide, 14-18 parts of chromium sesquioxide, 12-16 parts of nickel carbonate, 10-14 parts of manganese carbonate, 8-12 parts of cobalt oxide, 6-10 parts of magnesium hydroxide, 14-18 parts of manganous-manganic oxide, 12-16 parts of chromium carbide, 10-14 parts of tungsten carbide, 8-12 parts of polonium oxide, 6-10 parts of aluminum hydroxide, 2-4 parts of coupling agents, 1-3 parts of accelerants and 1-3 parts of defoaming agents. The magnetic core overcomes the shortcomings of the prior art, thestrength of the magnetic core is effectively improved, damage to the magnetic core in the assembly process is prevented, the service life of the magnetic core is greatly prolonged, use effects are good, characteristics such as the impedance, the Curie temperature and magnetic conductivity of the magnetic core are effectively improved, and the magnetic core is small in internal stress, superior inperformance and suitable for popularization.