A tidal energy seawater desalination system wherein a seawater evaporation tower is configured with a vacuum pump which connects with a tidal energy power device, and connects a seawater evaporation tower via pipelines, an output end of the pump connects a steam condensation tower via pipelines; alternatively the evaporation tower comprises a floating barrel and a stationary barrel, the floating barrel connects with the power device, the top of the stationary barrel connecting the steam condensation tower via pipelines; the pipeline introducing the steam into the condensation tower first connects a steam pressure tank, a steam turbine connects the tank via pipelines, the power output shaft of the turbine connects generator sets, and in turn, the turbine connecting the condensation tower via pipelines, such that the system is also a power generation system; on the offshore of which is provided with solar water heater and wind driven generator.