In recent years, there is an explosive growth in internet users which requires a broadband access network with high capacity and better flexibility i.e. they require services in "anywhere-anytime" manner. The FiWi technology provides such services to the user at lower cost with high bandwidth. The key issues in FiWi network are ONU Placement, Survivability and Energy Saving.This work focuses on ONU placement problem and presents an efficient algorithm to solve this problem.