A slide rail mechanism is configured to be mounted to a first post and a second post of a rack. A transverse space is defined between the first post and the second post. The slide rail mechanism includes a first slide rail kit and a second slide rail kit. Each of the slide rail kits includes a fixed rail and a movable rail longitudinally movable relative to the fixed rail. The two fixed rails are respectively connected to the two posts, and are located outside the transverse space. Each of the fixed rails is formed with a passage corresponding to inside of the transverse space. Each of the movable rail is configured to be movably mounted to the passage.