Abstract: Taking polyethylene terephthalate resin for bottle as the research object, the intrinsic viscosity of the sample was determined according to GB 17931-2003. The effects of solution concentration, sample dissolving temperature, sample dissolving time, sample stirring rate and other parameters on the determination results were analyzed. According to JJF 1059.1-2012 the standard uncertainty component introduced in the determination process was evaluated. The results show that the most important factor affecting the measurement uncertainty of viscosity of polyester chips was the solution concentration. The sample stirring rate, the sample drying treatment and the repeatability of measurement also had a great influence on the determination results. Solvent and solution flowing time had little influence on the determination results.