Abstract: It is very difficult to quantitatively characterize fracture complexity index for multiple hydraulic fracturing in shale gas horizontal wells,and there is no method available at present on how to optimize fracturing design nowadays.Therefore,fracture complexity index characteristic is further analyzed while the distribution density of branch fractures and seepage flow interference overlap area between them along the main hydraulic fracture are taken into consideration.New fracture complexity index is not a range but a specific value.So the object of fracturing design is to maximize fracture complexity index through optimization and control fracturing treatment parameters,predicting post-fracturing performance and effective period,etc.Based on the systematic works,a new multiple fracturing design method and workflow were established under the condition of horizontal stratification and/or texture fissures.In addition,it is a quantitatively descriptive method of distribution density and length of each natural fractures.This new method was verified in a horizontal shale gas well in Jiaoshiba area and the averaged open-flow capacity rate is 26% greater than none-treated well.The new fracturing design method can improve post-fracturing performance to a great extent and so that it has a great significance in the exploration and development of shale gas in China in the future.