The invention discloses a graphite boat in-and-out transition loading lock, which comprises a lock cavity, an outer door, and an inner door, wherein the outer door and the inner door are used to seal the lock cavity. A slide rail and a tray for bearing a graphite boat are arranged in the lock cavity. The slide rail is arranged between the outer door and the inner door. The tray is arranged on the slide rail through a slide block. The lock cavity is provided with a driving mechanism for driving the slide rail. A graphite boat in-and-out loading lock method comprises the following steps: opening the outer door, pulling out the tray along with the slide rail, putting the graphite boat on the tray, then pushing back the tray into the lock cavity, closing the outer door, vacuumizing the lock cavity, after the designed indexes are reached, opening the inner door, pushing the slide rail to the inner door by the driving mechanism, and driving the slide block, tray, and graphite boat by the slide rail until the graphite boat is moved out of the lock cavity. The graphite boat in-and-out transition loading lock has the advantages of high automation degree, convenient operation, and high efficiency, and does not affect the service life of graphite boat.