Abstract: In order to ensure the accuracy of laboratory test results, the uncertainty of the determination of indicative polychlorinated biphenyls in fish by gas chromatography was evaluated. According to the national Food Safety standard, National Food Safety Standard Maximum Levels of Contaminants in Foods (GB 2762-2022), the content of PCB28, PCB52, PCB101, PCB118, PCB138, PCB153 and PCB180) in the "measured" samples was determined as the total content of PCBs. Then, the polychlorinated biphenyls (PCBs) measurement model was re-established according to the "measured" and detection standard, and then the weight of uncertainty affected by the measurement model on test results were analyzed and evaluated. After evaluation, the measurement result of PCBs in quality control fish samples was 149.1 μg/kg, and the relative extended uncertainty was Ur=2.9%, k=2. The contribution of uncertainty was measurement repeatability 70.8%, sample weight 0.025%, internal standard volume 1.8%, sum of concentration ratios of each target in sample solution 27.3%.