The invention discloses a method for purifying ecological compound sludge water body. An anaerobic pond, an intermediate settling pond, an ecological compound sludge system and a sludge reflowing system are sequentially arranged; sewage enters the anaerobic pond to remove organic matters and release phosphor and then enters the intermediate settling pond to generate solid-liquid separation; the separated supernate flows into from the upper part of the main ecological compound sludge reflowing system, sequentially flows through an ecological area, a nitration area, an activated sludge phosphor-removing area and a water collecting area and is then drained out of the main ecological compound sludge reflowing system; the activated sludge separated by the intermediate settling pond directly enters the activated sludge phosphor-removing area of the main ecological compound sludge system and is then subjected to the solid-liquid separation through the water collecting area; and the supernateis drained out of the main ecological compound sludge system. The sludge reflowing system is arranged between the activated sludge phosphor-removing area at the bottom of the ecological compound sludge system and the anaerobic pond and is convenient for the anaerobic phosphor-releasing function of the sludge. The invention has the advantages of stability for operation, low investment operation expanse, convenience for management, high-efficiency removing effect on pollutants and the like.