Linear plasma devices offer an effective way to conduct the plasma-wall interaction studies and contribute to a basic understanding of edge plasma physics. A new platform at Harbin Institute of Technology for Plasma Surface Interaction experiments (HIT-PSI) is a newly-built linear device at the stage of commissioning which is capable of simulating high heat power deposition on divertor targets similar to tokamak conditions. Therefore, numerical simulations to evaluate the plasma characteristics is essential for designing and guiding the experimental conditions in HIT-PSI. In this work, the three-dimensional edge transport code EMC3-EIRENE has been used to investigate the plasma parameter distributions in HIT-PSI with the puffing and pumping systems involved. The effects of the heating power and target position on the distribution of electron density, electron temperature, and particle and heat fluxes have been investigated by EMC3-EIRENE. Particularly, the reduction in the electron density with the puffing fluxes has also been studied by analyzing individual atomic and molecular processes. Finally, the influence of varying pumping speeds on plasma parameters has been investigated in detail by adjusting the recycling coefficients at the two pumping ports.