The invention discloses an improved shell-and-tube heat exchanger with large stroke. The heat exchanger comprises a housing, wherein a hot fluid inlet and a hot fluid outlet are formed in the two ends of the housing respectively; a cold liquid inlet is formed in the top, close to the hot fluid outlet end, of the housing; a cold liquid outlet is formed in the top, close to the hot fluid inlet end, of the housing; a plurality of rotational flow structures, heat exchange tubes and heat exchange components are sequentially arranged in the housing between the hot fluid inlet and the hot fluid outlet end; a plurality of rotational flow joints are arranged on the heat exchange tubes. According to the improved shell-and-tube type heat exchanger with the large stroke, the hot fluid enters from one end of the housing and flows out of the other end while the cold fluid collides in the reverse direction, so that the contact area is expanded, the stroke amount of the heat exchange is increased, and the contact time of the two fluids is prolonged.