The uncertainties existing in the process of food risk assessment have an impact on the reliability of chemical risk assessment results and the correctness of regulatory policies, which are caused by the effects of objective randomness, insufficient human understanding, and subjectivity of judgments. There is a general agreement amongst scientific experts that the uncertainties affecting the assessment of risks should be identified, assessed,managed, and communicated. The analysis of uncertainty can evaluate the credibility of risk assessment conclusions scientifically, identify influencing factors and sources effectively, and promote the transformation of risk assessment models. Food safety risk assessment has formed a relatively complete system in China, but there is relatively little research on uncertainty, in contrast. This article mainly introduces the source and classification of uncertainty, as well as the analysis, characterization, and communication of uncertainty from the perspective of risk assessors, in order to provide reference and reference.