Abstract: In order to explore the copper loss and the temperature of the stator winding under normal conditions and different air-gap eccentricity forms in synchronous generators, firstly, we derived the corresponding expressions of magnetic flux density. Then, we established the three-dimensional finite element model of the CS-5 generator and calculated the copper loss and the temperature of stator winding under different loads and fault degrees. Finally, we measured the stator winding temperature on the CS-5 prototype generator. The results of simulation and experiments are generally consistent with the theoretical analysis conclusions. It is shown that the temperature of the straight section is higher than that at the end. The stator winding temperature in normal conditions is lower than that in the air-gap eccentricity conditions. And with the increase of eccentricity and load, the loss and the temperature show an increasing trend. In addition, the stator winding temperature in the minimum air-gap point is higher than other parts under static air-gap eccentricity.