Unmanned Aerial Vehicles (UAV or drone) equipped with sensors have been recently emerging as a new platform for remote sensing. Compared with satellite and airborne remote sensing techniques, drones can fly at low altitudes and at slow speeds, allowing them to take ultra-high spatial resolution imagery as frequently as needed. Owing to the above advantages, drones have been rapidly applied in ecology and conservation biology. In this review, we first briefly introduced the history of drone technology, the composition and classification of the drone platform, and its advantages in different research fields. Then, we provided an overall review of recent progress in drone ecology, and other research fields, such as habitat monitoring, plant phenology surveys, and animal monitoring. Finally, after analyzing the current status of this emerging field, we discussed the limitations of drone imagery analysis and regulations, and potential application prospects.