Understanding and controlling the gas flow at the nanoscale has tremendous implications in the fields of separation science, catalytic reactions, and energy storage, conversion and extraction. However, the gas flow behavior at the nanoscale is significantly different from that occurring at larger scales. In this work, we focus on a real gas effect, stemming from a strong gas intermolecular interaction force at high pressure and an un-negligible gas molecule volume at the nanoscale, on gas flow through nanoporous shale. An analytical and unified model is developed and validated with the published results of the Lattice-Boltzmann equation and experiments. This unified model covers all gas flow mechanisms, including viscous flow, slip flow and transition flow, and captures the real gas effect, which enhances flow capacity through nanoporous shale. This unified model is a ready-to-use tool for fast and accurately modeling gas flow through nanopores, and provides a basic foundation for numerical simulation and production prediction in shale gas reservoirs. (C) 2017 Elsevier Ltd. All rights reserved.