Gas transport in nanopores is a fundamental issue for reservoir simulation, with important implications for economic development of shale gas reservoirs (SGRs). Gas transport in nanopores in SGRs is significantly different from that in conventional reservoirs due to the shales serving both as the source and gas reservoir rocks with abundant nanopores. In this review, we first describe the characteristics of shales, then review and assess gas transport mechanisms and simulation in nanopores in SGRs. A new method for transport mechanism classification of bulk gas in nanopores, is proposed on the basis of a set of discrimination parameters developed in this paper. Finally current challenges in modeling gas transport in nanopores and some key scientific issues to be further studied in future are outlined. Keywords shale gas reservoirs; nanopores; transport mechanism; model; simulation; real gas effect; confinement effect