An attempt of large eddy simulation (LES) in a model combustor is performed, and a number of critical issues, such as grid size, incoming flow, wall boundary, physical sub-model and result sampling, are discussed. The computed results are compared with comprehensive experimental measurements, and illustrate that the mean axial velocity and temperature distributions inside the combustion chamber can be fairly well predicted by LES. However, for LES to become an accurate and cost-affordable tool for advanced combustion system development, some basic issues remain to be addressed and more validation studies are required. In addition, considerable computing power is needed in order to catch both low and high frequencies of flow motion in actual turbulent combustion systems.