A water sampling method includes acquiring, by an unmanned aerial vehicle, a sampling depth at which a water sample is to be taken. The sampling depth is sent by a portable electronic device or is a preset default depth. The method further includes calculating a descending distance based on the sampling depth and a distance between the unmanned aerial vehicle and a water surface, controlling the water sampler to descend for the descending distance, sampling, by the water sampler, a water sample, and sending a sampling result to a ground station or the portable electronic device.