A conveying unit (100) of a web, or sheet, of paper, or similar products, arranged to transfer along a transfer direction the web, or sheet, of paper, having a support (41) having a lateral surface (42) provided with at least one peripheral suction groove (43). A suction belt (45) is arranged to move along a closed trajectory (46) comprising the suction portion (44). The suction belt (45) is configured to air-tightly engage the suction portion and provides at least one through hole (47) arranged to be positioned at a respective suction portion (43) in order to cause a suction effect on the web, or sheet, and to transfer it from a first point P1 to a second point P2 of a production line of paper products. It is, furthermore, provided a driving device (60) configured to move the suction belt (45) with respect to the support (41).