This paper presents a fast and effective methodology for optimization injection molding process parameters of short glass fiber reinforced polycarbonate composites. Various injection molding parameters such as filling time, melt temperature, mold temperature and ram speed were considered. The methodology combines the use of Taguchi approach and a CAE flow simulation software which was used to simulate the injection molding process and to predict the fiber orientation. This method can replace the traditional `change-one-parameter-at-a-time' approach which is very inefficient, costly, time consuming and almost impracticable to yield an optimum solution. In the mean time, the microstructures were examined with a scanning electron microscopy to determine the fiber orientation and shear layer thickness to check the results of CAE simulation. The results indicated that three distinct layers (frozen layer, shear layer and core layer) are observed from surface to core at various injection molding conditions. The fiber orientation is perpendicular to the melt flow direction in frozen layer and core layer, but it has the opposite direction in shear layer. From the CAE analysis, we have gotten the optimum process parameters to obtain the thickest shear layer that was our target.