Navigation problems of unmanned air vehicles(UAVs)flying in a formation have been inves-tigated recently,where collision avoidance is a significant issue to be addressed.In this paper,we study resource allocation and power control for radar sensing in a multi-unmanned aerial vehicle(multi-UAV)formation flight system where multiple UAVs simultaneously perform radar sensing.To cope with mutual radar interference among the UAVs,we formulate a joint channel allocation and UAV transmission power control problem to maximize the minimum signal-to-interference-plus-noise ratio(SINR)of the radar echo signals.We then propose a computationally practical method to solve this NP-hard problem by decompos-ing it into two sub-problems,i.e.,channel allocation and transmission power control.An iterative channel allocation and power control algorithm(ICAPCA)is proposed to jointly solve these two sub-problems.We also propose a reduced-complexity greedy channel allocation algorithm(GCAA),which can also be used to provide an initial solution to ICAPCA.Simulation results show that the proposed ICAPCA and GCAA can improve the minimum SINR and radar sensing performance significantly.