Abstract: The evaluation system,critical steps and key parameters for shale gas sweet spots were discussed in this paper.A case study was carried out in Jurassic of Jiannan area of the Sichuan Basin.By means of the evaluation system,the geologic features of sweet spots in shale gas reservoirs were analyzed,the distribution pattern of sweet spots were predicted,and the arrangement of exploration wells were put forward,resulting in good effects.It was concluded as followed.1) Different from conventional petroleum evaluation,the evaluation and explorationof unconventional shale gas demanded an unconventional approach combining geology with engineering.Geology,geochemistry,petroleum engineering,lithomechanics and petrophysics all contributed to the evaluation.2) The success of long-distance horizontal fracturing in well Jianye HF-1 proved good potential for shale gas exploration in Jurassic of Jiannan area.3) The maps of shale thickness,ω(TOC),R_o and burial depth might guide shale gas sweet spots exploration.