Abstract: FEKO is an advanced simulation tool which is applied to analyze 3D electromagnetic field.Physical optics is an important algorithm in FEKO, which can simulate electrical large-scale targets, such as artificial corner reflector.In paper, pyramid trihedral angle's RCS curve is obtained with PO. The simulation result is good consistency with theoretical max value.Through analyzing RCS curve,it can help choose the right type of corner reflector and provide guidance on how to set up CR in the fields.When RCS of artificial corner reflector achieves maximum,it is easier to recognize CR from SAR and increase monitoring accuracy.