High-speed permanent magnetic generator (HSPMG) is common and important power production equipment in distributed generation systems. According to the structure characteristics of a 100kW level HSPMG, the mathematical model and physical models for its two-dimensional electromagnetic and thermal analyses are established, and the electromagnetic field of generator working in steady state is calculated by using finite element method, from which loss distributions in machines operating under different situations are determined. Taking these losses as the distributed heat sources that used in thermal analysis, after the determination of associated heat transfer conditions, the two-dimensional no-load temperature field is analyzed. Considering the variation of heat sources and air heat transfer capacity under different operating situation, the influence of generator operating speed on HSPMG no-load temperature distribution is studied. The obtained conclusions may provide useful reference for the design and research of HSPMG.