Large eddy simulations of a complex flow past a 2D square cylinder with the generated inflow turbulence are carried out. In this study, the velocity fluctuations at the inflow boundary are generated artificially using a method proposed by Lee et al. (1992) based on a prescribed 3D energy spectrum in wave number domain. Computations are carried out with two different turbulence levels of the approach flow, i.e., 2% and 6%. A computation without inflow turbulence is also conducted for the comparison. The effects of inflow turbulence on the predicted results are then discussed. Integral parameters and time averaged velocity distribution are much influenced by the velocity fluctuations at the inflow boundary.