The utility model discloses a shell -and -tube heat exchanger, it includes shell -side barrel, the pipe box bucket body, tube sheet, heat exchange tube, draw bar assembly and baffling board, and just both ends fixed connection is on the tube sheet in the shell -side barrel in the heat exchange tube setting, and the heat exchange tube passes the baffling board, and the baffling board is fixed along the axial direction parallel equipartition by draw bar assembly, and draw bar assembly includes the connecting portion of fixed connection on the tube sheet and pegs graft in the grafting portion of baffling flange reason that wherein, grafting portion is platelike structure. For prior art, the utility model discloses shell -and -tube heat exchanger has following advantage: 1 ) simple structure, draw bar assembly have the function of pull rod, distance sink tube, bypass damper and assembly guide rail simultaneously, and the stringing that has increased the baffling board is regional, under equal heat transfer load, have reduced the internal diameter of shell -side barrel, have increased the shell side velocity of flow, 2 ) draw bar assembly can play bypass damper's effect, can effectively prevent the by -pass flow between casing and the tube bank, is favorable to the heat transfer.