Disclosed are a water purifier and a control method thereof for controlling a main body by executing an artificial intelligence (AI) algorithm or a machine learning algorithm in a 5G environment established for the Internet of things. The control method of the water purifier according to the present disclosure includes a photographing step, a scanning step, a recognizing step, a calculating step, a determining step, and a water discharging step. When the water discharging step is initiated, the distance sensor generates real-time height information on the water surface, and may stop discharging water before a real-time height exceeds the highest point height.