Abstract: Water bursting in pit floors is a typical catastrophic process. A catastrophic theory was applied in water bursting in pit floors for the first time. Through the research on the instability of energy in the floor system of coal mine, a cusp catastrophic model applied to forecasting water bursting in the floor was put forward. The formulas of the critical stress, the strain and the released energy of the instable floor were developed.So, a new theory approach was offered for the forecast of water bursting in mine.