In this paper, a definition of human factors analysis(HFA) is given, the importance of HFA to man-machine system design and the system reliability is described. A series of problems in HFA are pointed out: the difficulty of HFA, cognition to human factors-individual, group, organization, the relationship between environment and human behavior, methods of human reliability analysis(HRA), mechanism of human error, objectivity and consistency, usability of data, culture factors, and HFA on organization and management. At last, current ...