In view of high labor intensity, low efficiency and great harm to operators of manual spraying of fishery drugs, a new automatic spraying machine for fishery drugs based on hydraulic propulsion is designed in this paper. The machine takes FRP ship (fiberglass reinforced plastic ship) as carrier, and is driven by a DC self-priming water pump, powered by lithium battery and propelled by spraying. It consists of the hull, propulsion device, steering system, drug delivery system, radio remote control system and pipeline. The prototype test results show that the average speed of the machine is 1.0 m/s, dilution ratio range is 1:1 000 to 1:5 000, and practical efficiency is 460 m2/min, which is 160% higher than that of traditional manual spraying. Remote control of fishery drug spraying will guarantee the safety of operators and avoid waste and environmental pollution due to much drug spraying. The research shows that the application of this machine will provide a method of movable online mixing and underwater spraying. It has a positive impact on precision aquaculture.