Abstract: Palmer's P-3D fracturing pressure decline curve analyzing model is established in this paper.The paper also takes the fracture propagation after shut-in according to the criterion of stress intensity factor into cons-ideration and the reason of change of matched pressure with time during shut-in is discussed.In addition,this paper points out that it is important to use corresponding pressure decline analyzing model for different formation conditions.Effective fluid-loss coefficient,fracture geometry parameters and toughness of rocks will be determined by using the met-hod suggested in this paper.