Abstract: The density of thermal barrier strips of polyamide used for thermal barrier profiles of aluminum alloy determined by immersion method in GB/T 1033.1-2008 was compared with the results given by method of determining the density for precious metals in GB/T 1423-1996. Theoretical calculation showed that the deviation of density caused not by experimental error, but by improper formula application. Immersion method in GB/T 1033.1-2008 proofed correct only under the limitation in which the effect of wire could be ignored. As normal test conditions fail to satisfy such limitation requirement, method in GB/T 1423-1996 is recommended in consideration of its rationalities and universality.