As a wind power generation method, directdrive permanent synchronous windpower generator had the advantages of simple structure, low cost, and reliable operation, so it had potential application value in the wind power generation field. Taking a 1 200 kW directdrive permanent magnet synchronous windpower generator as the research object, the coupling analysis of electromagnetic field, temperature field and thermal stress field was carried out, and the influences of temperature change and thermal deformation on the properties of permanent magnet, copper wire and other electromagnetic materials were considered, achieving the convergence of electromagnetic performances, temperature and deformation, so that the performances of the generator could be more accurately analyzed. The stator winding optimum design of the generator was carried out through the multiphysicalfield coupling analysis method, which made the winding design more reasonable. The conclusions had certain reference value for the design of directdrive permanent magnet synchronous windpower generator.