We report results of molecular dynamics simulations of melting and premelting of single-walled carbon nanotubes (SWNTs) with different types of point defects, namely, the Stone-Wales defect, vacancy defect, and impurity defect. Using the Lindemann parameter, we found that the melting temperature of perfect SWNTs is around 4800K. We further show that premelting occurs in the regions close to the defects with premelting temperatures of 2600K for the Stone-Wales defect and3200K for the cavity defect. The SWNTs with Si impurity defects are thermally stable up to 3800K.