After small unmanned aerial vehicles (UAVs) or drones became commercially available, it has opened new prospects for their applications in emergency recovery, search and rescue operations, event tracking, and goods delivery. Flying Ad hoc Networks (FANETs) is a version of a popular mobile ad hoc network (MANET) paradigm. It is concerned with the deployment of multiple small UAVs. FANETs possess some unique characteristics, if compared to other kinds of ad hoc networks, and create some major challenges to the research community. One of the problems is designing FANET routing protocol. The protocol must form an effective route between UAVs and adapt it to the rapidly changing topology in real time. The performance of AODV and OLSR routing protocols in mini-UAV ad hoc networks is investigated with ns-2 simulation tool. In this paper, AODV and OLSR routing protocols were studied in order to choose the best of them for flying ad hoc network of mini-UAVs.