Abstract: Aiming at the uncertainty in the process of missing dimensional measurement in industrial CT systems, the error sources that may cause uncertainty are analyzed, and the measurement uncertainty is studied based on the GUUM method. The test results show that the proposed analysis method can meet the evaluation requirements of the uncertainties of missing dimensional measurement in industrial CT systems. Among them, the errors in the measurement process, the spatial resolution, the density resolution of the CT system, the pixel size of the plate detector, and the system error are the most important reasons for the synthesis uncertainty.