Belonging to the technical field of sewage treatment, the invention provides semi-submersible sewage treatment aeration equipment. During work, airflow firstly enters an air pipe from an external compressor, passes through a winch wheel and a guide wheel and then enters an airflow distribution block, the airflow sprayed out of the distribution block enters air valves of a main shaft, a first spray rod and a second spray rod are at a 180-degree symmetrical distribution state on a roller, and a first air valve and a second air valve on the main shaft are at a 90-degree distribution state on the main shaft, therefore when high pressure airflow flows to the first air valve and the second air valve, between the two air valves, only the submerged one can be opened, and the other one is at a closed state, during reversing, a first reversing roll encounters a first reversing rod, the roller rotates, the valve core of the first air valve is released out of an air hole, the first air valve is closed, at the moment, the roller further rotates under an inertial effect until the valve core of the second air valve enters the air hole, the second valve is opened, the airflow is sprayed out from the second spray rod, and the equipment starts reverse running.