The invention belongs to a guard bar cleaning device, and particularly relates to an automatic cleaning system for lake guard bars. The automatic cleaning system comprises a base, a fixing base, a pressurizing module, a water storage pond, a spraying module, blocking modules and floating bodies. The base is fixed to a shore side; the fixing base is installed inside the base, vertical sliding grooves are formed in the front and back end faces of the fixing base, and electromagnetic strips are arranged inside the portion, deviating from the sliding grooves, of the front and back end faces of thefixing base; the pressurizing module is installed inside the fixing base, and the pressurizing module presses water into the water storage pond by means of rotation of a fan; the water storage pond is used for storing the water pressed in by the pressurizing module, and a pressure gauge and a water valve are arranged on the water storage pond; the spraying module is located at the top end of thebase, and the spraying module utilizes the water stored inside the water storage pond for cleaning the lake guard bars; the blocking modules are located on the front and back sides of the fixing base,and the blocking modules are used for blocking a through hole in the fixing base; the floating bodies are installed at the lower ends of the blocking modules, and the floating bodies are used for pushing the blocking modules to move upwards. The lake guard bars can be automatically cleaned and the labor maintenance cost is lowered.