Abstract: Marine shale is the main sweet spot of marine shale gas reservoirs in China. The marine shale gas features complex accumulation mechanism, worse physical properties, and diverse fluid occurrence forms. The quality evaluation on marine shale gas reservoirs is important for sweet spot optimization in shale gas exploration and development, and reservoir quality is mainly evaluated by geophysical logging. This paper summarizes the geological characteristics of marine shale gas and the current problems on hydrocarbon exploration and development, introduces the pore-, core- and logging-scale petrophysical analysis technology, and also the prediction techniques of the above key parameters according to the key geological quality parameters of gas shale such as organic matter, reservoir property and gas bearing property, and the key engineering quality parameters such as brittleness index, stress difference and fracture toughness, establishes the comprehensive logging evaluation system for shale gas reservoir quality classification, i.e., sweet spot optimization, and demonstrates the technology application effect and applicability by actual examples. Finally, it points out the existing problems, and puts forward new ideas and future development trends.