Abstract: In this paper the influence factors achieving optimum carbon coated magnetite isothermal reduction rate had been studied.Bituminous coal and anthracite were used as carbon source,and carbon-coated ore powder with a grinding time of 105 s had been used for test in a modified dynamic reduction reactor.Weight loss state of iron ore powder coated with carbon source at different temperatures for both bituminous and anthracite were measured.The rate equations under three restrictive factors are combined with the multiphase reaction rate equation.The fitting curve and the rate constant k of the equation are obtained by linear fitting.Then the maximum likelihood method is used to obtain the D3 model as the best model.That is,the gas phase is a restrictive link,and the developed model equation is G(α)=[1-(1-α)^1/3]².Based on the developed model he calculated activation energy E_a is 52.317 kJ/mol.