Abstract: In order to evaluate the temperature distribution characteristics of an generator unit, the temperature analysis model of an generator unit was built based on CFD method and it was numerically solved by co-simulation method. Results show that the error between the simulated values and experimental values of muffler front cover temperature is 4.9%.This indicates that the model built in this work is effective. Cell surface velocity distribution of engine cylinder head and crankcase is uniform and there is no zero-velocity zone. The maximum temperature of the engine body is about 200 ℃, and the maximum temperature of the stator and its winding coil is about 120 ℃, which not exceed that maximum temperature bearing value of 150 ℃. The maximum temperature of inverter system is 91.66 ℃. Temperature analysis results can provide quantitative data support for the evaluation of generator unit cooling performance.