The utility model discloses a modular coagulating sedimentation device belongs to water, sewage and effluent treatment plant, and it is big to have solved traditional coagulating sedimentation tank area, maintains inconvenient shortcoming. Modular coagulating sedimentation device includes the base, has set gradually to mix according to water flow direction on the base and has congealed district, flocculating reaction district, precipitation separation district and pH regulatory region, and equal seal installation communicates in proper order between adjacent area, mix the upside setting of congealing the district and being close to the flocculating reaction district, mix the space of congealing the district below and be used for placing auxiliary mechanical equipment, simultaneously, thisdevice adopts multiple spot internal circulation system, the sewage return -flow system in flocculating reaction district promptly, and the return sludge system in precipitation separation district and the supernatant return -flow system of pH regulatory region improve the treatment effect. The utility model has the advantages of compact, area is little, unit area water production is big, strong adaptability, treatment effect stabilize, can reduce medicament consumption and reduce cost in a large number.