Abstract: An improved system for removing sludge from dam reservoir comprises a suction port, a delivery pipe, a float, a tug boat, several universal joints connected in the delivery pipe, a concentration alarming indicator, a boosting pipe, an ejector and a sludge consolidating means. The water of high static pressure is led through a boosting pipe into nozzles of an ejector so as to suck the air or muddy water near the bottom of a dam reservoir through the delivery pipe so that the sludge or sand existing deeply in the reservoir will be automatically discharged outside the dam without consuming electric or oil energy as driving a conventional pump.