Both tetrahydrofuran (THF) and 2-methyltetrahydrofuran (MTHF) are studied systematically at desired temperatures using molecular dynamics simulations.The results show that the calculated densities are well consistent with experiment.Their glass transition temperatures are obtained:115 K ～ 130 K for THF and 131 K ～ 142 K for MTHF.The calculated results from the dipolar orientational time correlation functions indicate that the "long time" behavior is often associated with a glass transition.From the radial and spatial distributions,we also find that the methyl has a direct impact on the structural symmetry of molecules,which leads to the differences of physical properties between THF and MTHF.