The invention discloses an island artificial porous system geothermal energy electricity and fresh water cogeneration system. The island artificial porous system geothermal energy electricity and fresh water cogeneration system comprises an artificial porous system, a geothermal well, a power generation device and a water purification device; the artificial porous system is arranged in the middleof an underground dense rock layer; the geothermal well penetrates through the dense rock layer and the artificial porous system; the power generation device comprises a flash tank, a steam turbine and a generator; an inlet of the flash tank is connected with the geothermal well; the water purification device comprises a fresh water tank and a condenser; the steam turbine is connected with a heatmedium inlet of the condenser; the fresh water tank is connected with a heat medium outlet of the condenser; a cold medium inlet of the condenser is connected with a water supply pump; a cold medium outlet of the condenser is divided into two paths; one path is connected with a drainage pipe; and the other path is connected into the geothermal well. Geothermal energy is adopted as a heat source and the output temperature of the geothermal energy is stable; the power generation power of the geothermal single well and the fresh water generating capacity are greatly improved through enhanced heatexchange of an artificial porous system; the island artificial porous system geothermal energy electricity and fresh water cogeneration system can be utilized in most islands; and the power generation and fresh water production can be simultaneously realized.