The invention discloses a novel corrugated plate piece for a welding plate type heat exchanger, which consists of triangular corrugated areas at the upper end and the lower end, and a rectangular corrugated area on the middle part. The plate piece has a hexagon shape; the triangular corrugated areas at the upper end and the lower end are distribution stream guidance areas; the rectangular corrugated area on the middle part consists of a rectangular heat exchange area on an upper part, a rectangular distribution stream guidance area on a middle part and a rectangular heat exchange area on a lower part; and after the plate pieces are laminated, bevel edges of the triangular stream guidance areas at the upper end and the lower end are folded to form inlet and outlet channels for a medium. The novel corrugated plate piece for the welding plate type heat exchanger has the advantages of simple structure, uniform fluid distribution and no dead zone.