Film cooling technology is widely adopted in aero-engine to lower the temperature of hot components such as combustor liner and turbine blade. Compared with a conventional cylindrical hole, a fan-shaped hole is expected to be more advantageous with higher film cooling effectiveness. To gain a further understanding of the influence of the fan-shaped hole geometric parameters as well as blowing ratio at the typical combustor liner operating environment of a high bypass ratio commercial aero engine, the flow and heat transfer characteristics of fan-shaped holes are numerically investigated. The influences of the plate thickness, hole exit width, cylindrical inlet length and inclination angle on the downstream flow structure and film cooling effectiveness are investigated. It is shown that geometric parameters have little effect on cooling performance at small blowing ratio, while the changing tendency of the cooling effectiveness might vary due to the cross effect of different parameters at large blowing ratios. Several kidney vortex structures were observed at different geometric parameters, which were considered to greatly influence the distribution of film cooling effectiveness on the downstream part of the cooling hole.