It is important to keep away from the ghost reflection point for the arrangement design of final optics assembly (FOA) in the high power laser facility. The high power output of the “SG-Ⅱ” upgrading laser, limited target field space and complicated ghost reflection distribution lead to the difficult design of the FOA. By using the ghost image analysis software designed by ourselves, we analyzed the ghost reflection distribution of the FOA. Then, the arrangement of two types of designs for the FOA was optimized. According to the characteristics of “SG-Ⅱ” upgrading laser, we obtained the design for the FOA, which can satisfy the system requirement exactly.