Island rainwater collecting system

The invention relates to an island rainwater collecting system which comprises an impounding reservoir buried underground, wherein the impounding reservoir comprises a waterproof impounding reservoir wall, a waterproof impounding reservoir bottom and a water-pervious impounding reservoir top plate arranged on a top opening of the impounding reservoir wall, and a filtering layer is arranged on the impounding reservoir top plate; a water collecting well is arranged in the impounding reservoir, a top opening of the water collecting well is higher than the filtering layer and is provided with a well lid, a wall of the water collecting well comprises an upper waterproof reinforced concrete well wall and a lower water-pervious concrete well wall, a reinforced concrete well beam is arranged between the waterproof reinforced concrete well wall and the water-pervious concrete well wall, and the water-pervious concrete well wall is lower than the bottom surface of the top plate of the impounding reservoir. The island rainwater collecting system can be used for collecting and filtering rainwater and providing domestic water for people so that people can use water conveniently, is highly practical, guarantees the development and maintenance of an island, and enables natural resources to be effectively utilized and protected.