It has been verified by many researchers that the lattice Boltzmann method has the ability to simulate the viscous fluid flow as precisely as the finite difference method. The incompressible viscous fluid flow in the inlet section of two-dimensional channel are computed by the lattice Boltzmann method. In this paper, the computed results by the lattice Boltzmann method are compared with the results using finite difference method, and are discussed for the concave velocity profiles at the initial stage of development channel flow.