A tube sheet system of a low-temperature economizer comprises a multi-hole steel plate, a tubular supporting body, an elastic seal ring, a fluoroplastic heat exchanging tube, a check ring, a snap spring and a flange buckle, wherein the tubular supporting body is arranged in an inner hole of the multi-hole steel plate, the outer side of the tubular supporting body is provided with a sealing groove,the tubular supporting body is internally provided with a stepped hole, the stepped hole is provided with an annular groove, and the lower end portion of the tubular supporting body is provided witha necking hooked bracket; under the elastic action of an elastic annular groove of the elastic sealing ring, the fluoroplastic heat exchanging tube is inserted into a taper hole of the elastic seal ring and abuts against the step of the stepped hole of the tubular supporting body; the snap spring is arranged between the bottom of the elastic sealing ring and an upper stepped hole of the check ringand used for pressing the fluoroplastic heat exchanging tube; and the flange buckle is arranged among a middle stepped hole of the check ring, the fluoroplastic heat exchanging tube and the snap spring and is provided with an inner hole. The tube sheet system of the low-temperature economizer is good in sealing, rigid fixing is achieved, the tube sheet system of the low-temperature economizer isreliable in fixation, not prone to ash accumulating and scale forming, resistant to corrosion, large in heat exchanging area, small in weight and size, compact in structure, convenient to dismount andlong in service life, and the heat transfer coefficient is increased. The tube sheet system of the low-temperature economizer can be widely applied to a deep cooling system of cold-fired power station boiler smoke.