The adsorption of molecule STO on GaN (0001) surface is theoretically explored by using a plane wave ultra-soft pseudo-potential method based on density functional theory. The simulated results indicate two 0 atoms are combined with two Ga atoms on GaN surface after adsorption respectively. The 0-0 line direction lies along the GaN [11 - 20] directions, and the Sr-Ti line direction lies along the GaN [10 - 10] directions, in accordance with experimental reports of (111) [1 - 10] SrTiO3 // (0001) [11 - 20] GaN. For the total interface energy of STO/GaN, the chemical interaction energy is dominant as the chemical bonding energy achieved 10.215-10.299 eV. (C) 2015 Elsevier B.V. All rights reserved.