The stress adjustment of the surrounding rock induced by tunnel excavation will result in the change of the elastic strain energy of the surrounding rock. The rock burst risk in areas where elastic strain energy increases sharply is high. Hence, the variation laws of elastic strain energy of surrounding rock during excavation of Micangshan Tunnel are studied based on elastic strain energy theory by 3D numerical simulation method. The study results show that: (1) The unloading of surrounding rock induced by tunnel excavation under high ground stress will result in stress redistribution of surrounding rock, and further result in serious variation of elastic stress energy around tunnel face; the elastic stress energy in area of tunnel face and that 7 m ahead of tunnel face reduces, and that in area behind tunnel face increases. (2) The amplifications of elastic stress energy in crown top, sidewall and base are 356%, 373% and 466%, respectively, which indicates high risk of rock burst.