In this paper, we present a direct numerical simulation of particle sedimentation in two-phase flow with four different boundary conditions. We demonstrate that different boundary conditions can result in quite different flow behaviors. Some interesting results are obtained. By redefining the computational domain at each time step according to the position of the particle, we construct an infinite channel, which can simulate the particle sedimentation accurately; the flow pattern of periodic boundary is quite different from the infinite channel because of the disturbed flow field; if the settlement is reached steadily before the closed bottom, the closed channel can also simulate the particle settled in the infinite channel; the fluidized condition slows down the particle sedimentation, which is very helpful for better using the boundary conditions.