The impacts of aromatic contents in the aviation jet fuel on the volume swell of fuel tank polythioether and polysulfide sealants were systematically studied in this research. The experimental results revealed the sealant volume swell was dramatically increased as the aromatic content in the fuel was increased. The volume of the PR 1440 polysulfide manganese cured sealant was shrunk when the sealant was soaped in the aviation fuel with aromatic volume content less than 8 vol. % for 28 days at 93°C. The volume of the tested polythioether sealants was never shrunk at the same operating conditions. The experimental results also demonstrated the addition of various additives into the aviation fuel could effectively increase the volume swell of the sealant, increasing the sealant sealing properties. The shrinkage of the PR1440 polysulfide sealant soaped in the low aromatic content fuel at high temperature may be attributed to the material high density, the well-arrangement of the material structure and the high cross linking degree of polymer. This may also explain the fuel leakage phenomena in some aircrafts injected with low aromatic contents fuel in China.