Pressure decline analysis for hydraulic fracturing is very important for the formation evaluation and the optimization of fracturing design. But in the practical application

some problems of the pressure decline analysis were existed such as the unverifiable closure pressure

inaccurate geometric parameters of fracture and lack of formation effective permeability. Another way of obtaining closure pressure based on analysis on the character of pressure decline after fracture closure was introduced to verify the analysis result of conventional methods at first. An optimization method to achieve the fracture geometric parameters was given on the basis of G-function and pseudo-3D fracturing model at the second. Then the method of achieving reservoir effective permeability with the pressure data of quasi-linear flow after fracture closure was proposed. At last

a case was analyzed with the improved method and the calculation results verify the suitability and accuracy of this method.