According to energy conservation from the destruction of rock catastrophe, a new calculation method of the length of fracture propagation in hydraulic fracturing is proposed, and assuming the crack extends to approximate ellipse, the width calculation model of fracture extension is established. By using this new method in Changsheng well of Jilin oilfield, And the maximum error between the productivity that calculated by using the new method and the actual oil production is anastomosing. the method is an innovation in parameter calculation of crack propagation with the destruction of rock catastrophe, and it supposes some new theoretical foundation for the design of fracture parameter optimization.