The electromagnetic field distribution of the in-home GaN-MOCVD reactor heated by induction was simulated by using finite element method (FEM), and the distributions of the magnetic field and the joule heat in the graphite susceptor were obtained. Then the distribution of joule heat was used as the applied load for the simulation of temperature. Based on heat conduction and heat emission models, the temperature distribution in the reactor and the susceptor were gained. In order to improve the uniformity of the temperature on the top surface of the susceptor, the conventional concentric placement of the susceptor in the reactor was changed into the eccentric placement, which effectively improved the temperature uniformity and increased the heat efficiency. The electromagnetic field distribution of the in-home GaN-MOCVD reactor heated by induction was simulated by using finite element method (FEM), and the distributions of the magnetic field and the joule heat in the graphite susceptor were obtained. Then the distribution of joule Based on heat conduction and heat emission models, the temperature distribution in the reactor and the susceptor were gained. In order to improve the uniformity of the temperature on the top surface of the susceptor , the conventional concentric placement of the susceptor in the reactor was changed into the eccentric placement, which effectively improved the temperature uniformity and increased the heat efficiency.