For comprehensive understanding of the formation behavior of $eta-Al_5FeSi$ phase in Al-Si-Cu alloys with the existence of Fe element, microstructure characterizations were performed using combined analysis of OM, SEM-EDS, XRD. Especially, experimental and predictive works on solidification events of $eta-Al_5FeSi$ phase as well as other phases formed together with $eta-Al_5FeSi$ have been carried out by using DSC analysis and Java-based Materials Properties software (J. Mat. Pro.). Primary and eutectic $eta-Al_5FeSi$ phases were able to distinguish from each other on microstructures by their morphological features. Primary $eta-Al_5FeSi$ phase was seen to have rough surface perpendicular to growth direction, indicating free attachment of solute atoms in liquid state. On the other hand, the eutectic $eta-Al_5FeSi$ phase was formed with plain and straight surface during eutectic reaction together with $alpha$-Al phase. The eutectic reaction of $eta-Al_5FeSi$ and $alpha$-Al phases was seen to be able to separate into each formation depending on cooling rate.