Stress-strength ratio model is usually applied to rockburst prediction in China and abroad, but uncertainties in engineering are not taken into account in this method. A fracture mechanics model of rockburst mechanism is proposed in this paper. This model is based on the assumption that rockburst is caused by microcracks which parallel to the free surface. These microcracks will fracture, extend, and mutually connect under external load. Then visible macroscopic crack is formed and finally rockburst happens. Furthermore, a rockburst risk probability model is proposed using reliability theory and stochastic FEM method based on Lamination spallation buckling model. The model was applied to engineering project calculation and the result manifested its rationality.