The invention discloses an on-water garbage can, and relates to the field of environment friendliness. The on-water garbage can comprises a solar energy ball, a PLC, a storage battery, an air pump, anair pipe, a water flow electric generator, a water suction pump, an air bag, a hollow pipe and four garbage can bodies, the four garbage can bodies depend on each other in pairs to form a cylinder, the hollow pipe is located in the centers of the four garbage can bodies, the PLC and the storage battery are mounted on the top of the hollow pipe, the solar energy ball is mounted on the PLC, the PLCis connected with the air pump, the air pump is connected with the air pipe, the air pipe extends into an inner cavity of the hollow pipe, and the lower portion of the hollow pipe is connected with the air bag. The garbage can can float on the water surface, floating garbage in the water can be collected, along with continuously-increased collected garbage, gravity is increased, a water level sensor detects that data are sent back to the PLC, the air pump is controlled to be started, the air bag is inflated, buoyancy is increased, a cornice of the garbage can can be kept under the water by 1to 3 cm until the can is full of the collected garbage, a worker can clean the garbage in time, the on-water garbage can be cleaned without ship arrangement, labor intensity is reduced, and treatmentcost is reduced.