Abstract: A mechanical model was figured out as for instability of the rockburst existing in coal bed. The essay applied the theory of modern nonlinear catastrophe to analyzing the transformation occurring to coal bed and it's rockburst. This experiment got the occurring conditions of coal-bed rockburst, the kick value of rockburst, and the expression of energy to release out when pressure pump happened. The conclusion of this research helps to improve the cognition of instability staying inside coal rocks and principle of occurrence of rockburst.