The utility model relates to a bidirectional circulating exchanger used on a screw pump water circulating heating system which is characterized by comprising an outer sleeve assembly and an inner core assembly, wherein the upper end part of the inner core assembly is inserted into the outer sleeve assembly; the outer sleeve assembly is in rotational connection with the inner core assembly; the outer sleeve assembly is formed by connecting first and second outer sleeves; the first and second outer sleeves are respectively provided with a first water inlet and outlet port and a second water inlet and outlet port; the inner core assembly comprises is sealing core with a center through hole and a sealing sleeve; the upper end part of the sealing sleeve and the lower end part of the sealing core are in sleeved fit and are fastened and connected by screw threads; a water inlet and outlet ring cavity is formed between the sealing sleeve and the sealing core; the sealing core is also provided with a water passing passage communicated with the water inlet and outlet ring cavity and the second water inlet and outlet port; the lower end of the sealing core and the lower end of the sealing sleeve are respectively in sealing connection with inner and outer pipes of a double-hollow pumping rod; and mechanical sealing structures are arranged between matched positions of the sealing core and the first outer sleeve and between matched positions of the sealing sleeve and the second outer sleeve. Due to adoption of the bidirectional circulating exchanger, by changing the circulating direction of water, the operating working conditions of two high and low heating temperatures are met.