In the fields of high risk and high safety such as aerospace and aviation, risk events occur frequently during the operation of large and complex systems. Probabilistic risk assessment is an effective means to evaluate event risks. Uncertainty analysis is the core method to analyze the credibility of safety risk assessment results, measuring the impact of uncertainty on the final consequences. Combined with the current engineering situation, this paper puts forward an uncertainty analysis technology based on evidence theory, the basic principle of evidence theory is expounded, and the quantitative analysis process, method and model of uncertainty based on evidence theory are given. And takes a filling system as an object for case analysis, which provides a technical basis for the application of evidence theory in risk uncertainty analysis in the high security field.