Abstract: Influenced by reservoir characteristic and wellbore structure, such as high permeability, strong heterogeneity, long sand control interval, many perforation clusters and so on, the fracture propagation morphologic is complex and the sand fracturing is hard to be carried out during the frac-pack treatment in Bohai Oilfield. Consequently, the screen-out happens in advance easily and the filling coefficient is lower than designed. The method of mini fracturing test G function analysis is applied to diagnose formation leakage type, determine fracture extension type, modify the fracture pumping design and finally form an optimization method of fracpack pumping. This method can greatly reduce the ratio of early screen-out and has a good effect on frac-pack construction. This paper introduces the theoretical basis, design principle and field application,which can be provided as a guide and reference on fracpack operation for other oilfields.