To accurately analyze the loss and heat of large hydrogenerator,the finite element models of 2D steadystate electromagnetic field,moving electromagnetic field and fieldcircuit coupling are established respectively.As an example,the losses of the rotor iron and damper winding of a 36 MW tubular hydrogenerator are calculated.Furthermore,the influences of 3 different electromagnetic field models on the thermal sources and temperatures are analyzed by 3D finite element calculation of the temperature field.The results are compared with the test data and indicate that the precision of the fieldcircuit coupling model is better.The losses of each damp bar are different and the heat of the damp bar at the lee side is larger than that at the windward with the full load.The maximal temperature of the rotor is located at the damper winding,instead of the field winding.The research is valuable for improving the calculation precision of the rotor losses and temperature field and enhancing the reliability of the hydrogenerator design and operation.