The invention discloses a solar unmanned boat for adjusting water temperature and relates to the field of unmanned boats and aquaculture. The unmanned boat comprises a boat body, a microprocessor, a propulsion module, a communication module, a GPS positioning module, a first temperature sensor, a power supply module, a refrigeration module and a solar module; the refrigeration module comprises a water pump, a cold liner, an evaporator, a direct-current compressor and a condenser, wherein the evaporator is a spiral copper pipe surrounding the cold liner; the solar module is arranged on the topof the boat body; the first temperature sensor sends a first water temperature signal of a water area to the microprocessor, a second temperature sensor sends a second water temperature signal in thecold liner to the microprocessor, the communication module is used for data transmission between the microprocessor and the upper computer, and the GPS sends a longitude and latitude value of the boatbody to the microprocessor. The invention also provides an adjustment method of the solar unmanned boat for adjusting the water temperature. The unmanned boat adopts the compressor for refrigeration,the efficiency of water refrigeration is improved, a flexible solar panel is laid, solar energy is collected and converted into electric energy, and energy consumption is reduced.