Formation control is crucial for multi-unmanned aerial vehicle (UAV) system. We presents a novel formation control method for a multi-UAV system. Non-Line-of-Sight (NLOS) situations are predicted and the formation is adjusted accordingly through the sharing of obstacle information obtained from the leader UAV that is equipped with a stereo camera. The minimum snap trajectory for control efficiency to compose the motion primitive is used. In addition, the relative position is estimated using range data between UAVs and the estimated results are used as the position values of the follower UAVs. Three formations are considered; linear formation for passage through a narrow area, pentagonal formation for environmental information acquisition, and rectangular formation for escorting
the lead UAV. The proposed method is verified in the simulation environment.