Abstract: In view of the unclear understanding of mechanism of gas slippage effect, the new recognition of the gas slippage effect was put forward through different types of gas experiments which are used for testing the permeability of Berea sandstone and shale samples. It is proposed that diversity in lower limits of types of fluid through the reservoir pore throat and fluid-solid interface tension leads to differences in fluid velocity at the interface.Besides, the gas slippage coefficient is related to rock type and gas type while pressure and temperature mainly affect the high-pressure physical properties of the gas. Meanwhile, a gas production equation considering slippage effect was established, based on Darcy formula and pseudopressure function. It is concluded that the influence of slippage effect on gas well productivity can be ignored in conventional gas well productivity evaluation and only considered in low pressure and low permeability reservoirs.