Abstract:This paper tries to identify the main cause of the accident through the thorough analysis of the stator circle short circuit accident happened to the generation of a certain power plant. It considers the cause of the accident as follows. Because of the different frequency of the electric network, the rotational speed of the generator, which is home made according to imported technology, will slow down, which leads to the cooresponding reduction of the pressure and amount of the wind produced by the rotor fan. This will affect the cooling effect of the generator. which speeds up the ageing process of the insulation material of the generator and the insulant intensity will thus drop greatly. This paper also points out that when importing foreign technology, we should pay attention to the coordination, analysis and study among different majors and different sujects.