A prosthesis carrying barrel suction-attaching joint with locking function, particularly a joint specifically for suction-attachment to a carrying barrel, includes a positioning mechanism, which forms, in a center thereof, a positioning pin hole for receiving a positioning pin to dispose therein. The positioning mechanism is provided, in a lateral direction, with a penetration passage and a vacuum release passage in communication with the positioning pin hole. The penetration passage has two ends on opposite sides of the positioning pin hole. One of the ends is provided with a regulation assembly and another one provided with a locking assembly. The locking assembly includes a constraint block for retaining the positioning pin so that a chamber for vacuum regulation is formed in the site where the regulation assembly is arranged. Pressing down the locking assembly allows external air to flow through the vacuum release passage into the chamber to release the vacuum.
