HAUSAT-2 is nano satellite with 25kg mass being developed by Space System Research Lab. in Hnakuk Aviation University. This paper addresses HAUSAT-2 small satellite thermal analyses and its verification at satellite system, electronic box, and PCB levels. Thermal model which is used for system-level and box-level thermal analyses was verified and corrected through thermal vacuum/balance test. The new board-level thermal analysis methodology, modelling high-power dissipating EEE parts directly, was proposed. The proposed methodology has been verified with test results.