Abstract: Wet-gas boosting is the conventional process that is used in the development stage of gas fields with low pressure and high water content. The salt deposition on the impeller of centrifugal compressor is prominent on site due to the existence of dissolved salt in the wet gas, so it is necessary to study the coupling of its internal multiphase flow. In the traditional researches on the flow inside the impeller of centrifugal compressor, grid division is conducted on the whole impeller, so the computation load is huge and the multiphase flow can be hardly investigated. Furthermore, there is no experimental data available for comparison and verification. In this paper, Eckardt impeller was taken as the study object, the periodic boundary condition was adopted and the single flow channel was taken as the computation area to conduct numerical simulation on its internal flow situations. Then, the simulation results were analyzed and compared with the experimental data. It is indicated that the periodic boundary condition model can reflect the actual flow situations inside the impeller accurately (e.g. the distribution of secondary flow, the generation and development of jet wake). The research results provide the basis for the following study on the coupling of complex flow inside the impeller.