Abstract: In order to improve the reliability of test results, the study aimed at evaluation of the measurement uncertainty in the determination of ethyl carbamate residues in Chinese Baijiu by UPLC-Q/Orbitrap HRMS. Based on evaluation and expression of uncertainty of measurement (GB/T 27418-2017), a mathematical model of uncertainty evaluation was established, and the sources of uncertainty were comprehensively analyzed, further each component was quantified and synthesized. The results showed that the main sources of uncertainty arose from the determination of the experimental accuracy/bias and its precision, the preparation of standard solution and curve fitting, and followed by other sources of uncertainty was relatively low. Furthermore, it was worth through our research when the expanded uncertainty was 8.00 μg/L for ethyl carbamate contents of 71.54 μg/L in Chinese Baijiu (k=2).