Energy conversion is the physical feature in physical process. Through analyzing the rule of energy variation in the process of rock damage and relations of the rule, strength, and integral destruction,the essential feature of variation of rock strength and the overall destruction under external load was reflected. From the perspectives of energy dissipation and energy release, based on previous research achievements and effect of intermediate principal stress, general form of energy release of rock based on stress distribution was presented. Combined with minimum principal stress, a new strength criterion was suggested. Results show that, it is feasible to study the effect of intermediate principal stress by using energy criterion. When the value of minimum principal stress is given, relationship between rock ultimate strength and distribution coefficient of energy release is linear. Moreover, with the increase of distribution coefficient of energy release, the ultimate strength of rock gradually decreases. New energy strength criterion can fully consider the influence of intermediate principal stress, which can make up the shortage of conventional rock damage criterions.