The aim of this study was to study the uncertainty sources for density measurements of HDPE bottles by impregnation method. Impregnation method was used to repeatedly measure the same batch of HDPE bottles for oral solid medicine, the measurement uncertainty sources were analyzed and the cause-effect diagram was depicted. A measurement model was established, each of the contributors to the uncertainty of the measurement results was evaluated respectively, and the combined standard uncertainty of the density measurement was calculated as well as the expanded uncertainty. The density of the HDPE bottles for oral solid medicine was measured to be （ 0.950± 0.002）g/cm3, with a dispersion between ± 0.002 g/cm3, which conformed the national standard. The main contributor to the type B uncertainty of the density measurement was the auxiliary liquid temperature.