Abstract: In the system reliability and safety assessment, the focuses are not only risk caused by hardware or software, but also risk caused by “human error”. This paper considers the effects of risk of human error on system, and presents a new risk assessment model of human error based on fuzzy logic used to determine risk prioritization of human error. The method not only considers the human error probability, but also integrates the error-effect probability and consequence severity into the risk assessment model to satisfy the objective of probability safety assessment. At the same time, the method can model the complex system behavior to deal with subjective, vague and uncertain information or knowledge and it is more realistic than traditional method. A case example is presented to demonstrate the proposed approach. The results show that the method is practicable, reliable and valuable.