Magnetic field distribution and magnetic circuit calculating method of micro rotational generator are researched.A single stator-single rotor micro generator with an overall size of Φ 7 mm×2 mm is designed.The formula of no-load air gap magnetic density is got by magnetic circuit analysis method.FEA is done for the micro generator model using magnetic field numerical simulation software.The main parameters of no-load magnetic field and the wave form of induced EMF are obtained.Comparing the results by magnetic circuit analysis and numerical simulation result

the error of air magnetic density is less than 2.32 % and the error of the maximum value of induced EMF is less than 2.57 %.The parameters of the magnetic field can be used in the design and analysis of the micro generator.And the results verify that the magnetic circuit analysis method can be used in the research of the micro generator.