Abstract: A new holistic methodology for Human Reliability Analysis（HRA） is proposed to model the effects of the organizational factors on the human reliability.Firstly,a conceptual framework is built,which is used to analyze the causal relationships between the organizational factors and human reliability.Then,the inference model for Human Reliability Analysis is built by combining the conceptual framework with Bayesian networks,which is used to execute the causal inference and diagnostic inference of human reliability.Finally,a case example is presented to demonstrate the specific application of the proposed methodology.The results show that the proposed methodology of combining the conceptual model with Bayesian Networks can not only easily model the causal relationship between organizational factors and human reliability,but in a given context,people can quantitatively measure the human operational reliability, and identify the most likely root causes or the prioritization of root causes caused human error.