Abstract: Shale gas reservoir is characterized by nanoscale porosity and ultra?low permeability, which usually has no natural productivity, and has to be economically developed by means of horizontal well and volumetric fracturing technology. The study on shale gas at home and abroad mostly focused on geological characteristic evaluation and development process technologies, with few theoretical approaches to its productivity by volumetric fracturing horizontal drilling process. The key to shale gas production research should be in exact description of multiple scale flow mechanism and fine characterization of complex hydraulic fracture networks. Through wide investigation and analyses, this paper discusses such a flow mechanism, reviews the model for multiple transverse fracture horizontal well test in shale gas reservoir, elaborates how to distinguish flow regimes and evaluate reservoir and fracture parameters according to different models, and systematically introduces the methods of numerical simulation for shale gas, including conventional numerical modeling, discrete fracture network modeling and finite element approaches. It is believed that the discrete fracture network modeling and finite element approaches will be the future research trend for numerical simulation of shale gas productivity