In recent years，with the rapid development of China’s nuclear power industry，nuclear generatorhas also been actively developed. Because the unit capacity of the generator is increasing，working life and operational reliability of the generator are also being tested. Among them，transient thermal running ability of the generafor is one of the key factors affecting working life and operational reliability of the generator. This paper mainly analyzed the negative sequence current and the transient negative sequence component of the generator during asymmetric operation. The paper has reference value for in-depth study of the generator negative sequence component.