A robust system that can enable small quadrotors to fly fully autonomously at high speeds in complex environments with only vision and imu. For non-professionals, it will be helpful that the drone is capable of executing the mission autonomously after being easily taught how to fly by human, while being able to avoid obstacles when flying. Our system contains all components including hardwares and softwares which has accurate and fast vision-imu based locallization, mapping, safe flight corridor generating, global/local motion planning and high performance flight controller to perform this task. the drone can fly at high speed reliably in a complex GPS-denied indoor environment, and relys on only onboard components on a 250mm frame while flying.