A top-and-bottom latch structure for a lock mainly includes a lock formed by a casing, and a lock tongue, a lock core, a handle spindle, and other components disposed in the casing. The handle spindle is provided with a first and a second protruding rod disposed at different angles, and is respectively provided with a first and a second braking piece above and under the handle spindle, so that the two braking pieces are respectively clamped by the protruding rods. The top-and-bottom latch structure for a lock further includes: two fixing members, respectively connected to the braking pieces; and tact switches, connected to a door panel by the fixing members via connecting rods. Therefore, when the door is closed, the tact switches once touching the door frame are embedded into the door frame and the fixing members move downwards to rotate the handle spindle and lock the lock tongue.