The utility model relates to a built-in flue gas quantity dividing control device of an economizer. The built-in flue gas quantity dividing control device comprises an inlet header, an outlet header, and a plurality of coils arranged between the inlet header and the outlet header; the built-in flue gas quantity dividing control device is characterized in that the control system further comprises at least one separator and a flue gas temperature regulating baffle plate, one end of the separator extends out of the outlet header and then goes into a flue between the inlet header and the outlet header to divide the flue, and the flue gas temperature regulating baffle plate is arranged on the separator to block one part of the divided flue. Compared with the prior art, the built-in flue gas quantity dividing control device of the economizer has the advantages of simple structure, obvious effect, flexible adjustment, available stepless regulation and the like.