The utility model provides a heat exchanger capable of preventing device flange seal leakage. According to the heat exchanger capable of preventing device flange seal leakage, a hook ring (1) and a floating head flange (4) are arranged on the two sides of a floating pipe board (2) respectively and a sealing gasket (3) is arranged between the floating head flange (4) and the floating pipe board (2); the hook ring (1) and the floating head flange (4) are connected into a whole through a stud (5) and the two ends of the stud (5) are fastened through nuts (6); dish springs (7) are arranged between the hook ring (1) and the corresponding nut and between the floating head flange (4) and the corresponding nut. According to the heat exchanger capable of preventing device flange seal leakage, the problem that the pre-tightening force of a bolt is reduced in device flange connection is effectively solved and long-term leakage-free operation of the heat exchanger is achieved.