Abstract: In this paper, a multi-sensor fusion technology for micro air vehicle formation crossing obstacles under low-precision GPS conditions is proposed based on the monocular vision positioning method, altimetry filter algorithm based on LiDAR, and the leading-following formation strategy of micro air vehicle. For verifying this technology, a complete set of the micro air vehicle formation test platform was established through the design of key modules such as the hardware architecture of the system, sensor distribution, airborne self-organizing network, and the software interface of the airborne formation ground station. The actual formation flying test of the outdoor test site was conducted on the base of the simulation verification of the visual positioning algorithm, time-domain filtering of laser data, and formation flying under the robot operating system. Finally, formation flying missions such as formation flying across multiple groups of door frame obstacles at random positions, online path planning, and one-key take-off and return were realized using this technology, verifying the feasibility of the technology in the outdoor complex flight environment.