The ultrasonic algae removal device is characterized in that it comprises a shell, a power supply system, a wireless signal transceiver system, a control system, a positioning system, a real-time algae detector, an ultrasonic system, a mechanical power propulsion system and a floating carrier; The power supply system includes power supply equipment and energy storage equipment to provide power supply for the whole algae removal device; The wireless signal receiving and transmitting system is connected with the control system to provide long-distance transmission of data; The real-time algae detector is connected with the control system, and the control system is connected with the ultrasonic system, wherein the real-time algae detector is used to detect the algae content and feed back the detection results to the control system, and the control system controls the ultrasonic system to remove algae or inhibit algae according to the detection results; The control system is also connected with the positioning system and the mechanical power propulsion system. The positioning system is used to set the travel route. The control system receives the set travel route and controls the mechanical power propulsion system to ensure the travel route of the algae removal device.