In this technology driven world, wireless networks take part a key role in helping a society to enhance their life style .Unmanned air vehicles connected in an ad hoc manner been used in various application from civil projects to military applications. Establishing reliable, secure connection among UAV nodes in FANET is bit challenging task due to high node mobility, environmental condition under which it is operated and minimum energy capability of nodes etc. Routing protocols used in such a network should have unique features that overcome the limitation to make reliable and secured connectivity between nodes. There are many viable routing techniques had been discussed by past researchers .In our study we have gone through in detail different routing approach used currently in Ad-hoc network , analyzed their merits and demerits and made performance comparison study among AODV,DSR and DSDV on FANETs using ns-3 simulator. Performance metrics used for comparison are network delay, traffic received, data dropped and throughput. This metrics are evaluated by varying node density and node speed. Our study results reveal that different protocols suits for different FANETs network situations.