The invention for use in connecting the lid of a portable electronic device to its body consists of a spindle, a spring, a turned part and a sliding part. The turned part includes a fixed part and a cooperating part. In the sliding part, there is a mating hole whose shape is identical with the cooperating part above. The turned part, sliding part and spring are locked on the spindle. One end of spring is against the spindle, and another end pushes the sliding part to the top. The turned part can rotates around the spindle, and the sliding part can slide along with the spindle. The cooperating part of the turned part can be switched between position held in the mating hole and the position out of the mating hole. The spindle fits one part in lid and body of portable electronic device, and the fixed part of the turned part fits another part in them.