The embodiment of the invention relates to a water surface detection method, a water surface detection device and an unmanned plane. The detection method comprises the following steps of controlling the unmanned plane to generate airflow, wherein the airflow is used for generating water surface waves; obtaining an image of an unmanned plane landing region; determining whether light spots exceedingthe preset quantity exist in the image or not; if so, determining the landing region existence water surface, wherein the light spots are in one region, and the brightness value of the region is higher than the brightness of the peripheral preset region. According to the embodiment, the unmanned plane is controlled to generate airflow, so that the waves are generated in the landing region including the water surface; next, whether the landing region includes the water surface or not is determined by judging whether the light spots exceeding the preset quantity exist or not in the landing region image; the harm caused when the unmanned plane lands on the water surface by mistake can be reduced.