Rockburst is one of the major engineering geological problems faced by the construction process of deep-buried tunnels. Accurately determining the possibility of rockburst occurrence and the rockburst level is of vital significance for engineering construction， and it also poses a great challenge to the geological investigation. At present， during the geological investigation of water conservancy projects， only the strength-stress ratio is taken into consideration when determine the rockburst in tunnels using the industry standards. To thoroughly assess the rockburst potential in a deep-buried diversion tunnel， this study first applied the linear elastic energy criterion （W_e=40~100 kJ/m3） based on survey data and measured in-situ stress results to preliminarily predict the rockburst level. The results indicated an elastic energy density of 45 kJ/m3 in the surrounding rock， corresponding to a moderate rockburst risk. Subsequently， a three-dimensional geomechanical model was established using the finite difference method to invert the in-situ stress field and simulate the excavation-induced unloading process. It is revealed that elastic energy concentration zones were primarily distributed along the tunnel sidewalls. The numerical results mutually validated the energy criterion predictions， both confirm the spatial characteristics of moderate rockburst risk， and moreover the velocity and distance of the rock mass ejection during rockburst in the surrounding rocks are quantitatively predicted， which provide a basis for dynamic support design， and proposed reference value to the rockburst prediction of the deep-buried long tunnels investigation in the other water conservancy projects.