The invention relates to the technical field of aircrafts, and particularly provides an unmanned aerial vehicle multi-distance obstacle avoidance method and an obstacle avoidance system. According tothe invention, firstly, a flight path of the unmanned aerial vehicle is set. Secondly, the obstacle information on a plurality of distance levels in the flight space of the unmanned aerial vehicle isacquired. At the same time, the current flight state information of the unmanned aerial vehicle is acquired in real time. Thirdly, a flight obstacle avoidance plan is formulated according to the obstacle information and the current flight state information. Finally, the unmanned aerial vehicle performs the obstacle avoidance flight according to the flight obstacle avoidance plan. According to theinvention, a plurality of obstacle avoidance mechanisms are applied in parallel, wherein the predictive obstacle avoidance can be realized especially for large barriers such as buildings existing on flight paths, as well as moving barriers within the range of a moderate distance. The defects caused by purely relying on a short-distance obstacle avoidance mechanism are fully overcome.