The invention discloses a full-serial plate shell heat exchanger which reduces the thermal stress of the structure to the minimum extent by adopting an assorting cylinder treatment mode. The structure of the full-serial plate shell heat exchanger mainly comprises an upper end enclosure, a lower end enclosure, an III-stage cylinder, a II-stage cylinder, a I-stage cylinder, a skirt, a lathed bundle, a fluid distributor and the like, wherein heat exchange of cold and hot media is finished in the lathed bundle, a shell formed by the cylinders, the end enclosures and an adapter tube is a main bearing element, the lathed bundle is arranged in the cylinders, and all cylinders are fixedly connected in series by an equipment flange through bolts. A channel consisting of the fluid distributor and used for stabilizing a first fluid pressure head is arranged between the cylinders; and a second fluid channel is communicated by a bypass adapter tube of all the cylinders. The fluid distributor comprises an upper baffle, a lower baffle, a drainage tube, an expansion ring and the like. The full-serial plate shell heat exchanger can solve the technical problems that a plurality of traditional simple serial plate shell type heat exchangers are serious in pressure drop loss, increase the equipment cost, waste land resources, are not beneficial to energy conservation and emission reduction, and the like.