针对加速器工业CT线性尺寸测量的不确定度评定，建立了工业CT尺寸测量模型，对测量中不确定度的主要来源进行分析，基于测量不确定度表示指南(GUM)法对工业CT线性尺寸测量不确定度评定进行研究。以6 MeV高能工业CT系统尺寸测量为例，分析了长度样块线性尺寸测量各主要的不确定度分量，对尺寸测量的不确定度进行评定，最终得出具有包含概率为0.99的扩展不确定度为0.09 mm，结果体现了工业CT尺寸测量的精度和可靠性，为工业CT尺寸测量结果的可靠度提供参考依据。

The evaluation of the uncertainty of accelerator industrial CT has always been one of the difficulties in the research and application of industrial CT. In order to evaluate the uncertainty of linear dimension measurement of accelerator industrial CT, an industrial CT size measurement model was established, and the main sources of uncertainty in the measurement were analyzed. Based on the Guide to the Expression of Uncertainty in Measurement (GUM) method, the evaluation of the uncertainty of industrial CT linear dimension was studied. Taking 6 MeV high-energy industrial CT system size measurement as an example, the main uncertainty components of linear dimension measurement of length samples were analyzed, and the uncertainty of the dimension measurement was evaluated. The result is an extended uncertainty of 0.09 mm with an inclusion probability of 0.99, which reflects the accuracy and reliability of industrial CT dimensional measurements. This paper provides a reference for the reliability of the size measurement results of industrial CT.