[Objectives] To determine the content of organic pollutants by CALUX bioassay. [Methods] According to JJF 1059.1-2012 Technical Specification for Evaluation and Expression of Uncertainty in Measurement, the determination results of organic pollutants were analyzed, various sources of uncertainty that may be introduced in the detection process were analyzed, and the mathematical model of uncertainty was established. Type A and B evaluation methods were used to calculate the components of uncertainty and extended uncertainty. [Results] In the range of 95% confidence interval, the determination result of organic pollutants was 6.59 pg/g fat, and the extended uncertainty was 0.076 4 pg/g fat, so the determination results of organic pollutants could be expressed as (6.59 ±0.076 4) pg/g fat (k=2). [Conclusions] This study can provide a basis for more accurate determination of organic pollutants.