A fastener structure for pliers contains: a first connecting arm, a second connecting arm, and a slidable fastener. The first connecting arm is rotatably connected with the second connecting arm to form a griping segment and a working segment and includes a holder which has two guiding rails. The first connecting arm also includes a first notch and a second notch, and the second connecting arm includes a locking seat. The slidable fastener is hollow and retains with the holder, and the slidable fastener includes two guide posts, a positioning plate, and an elastic locker mounted on the positioning plate to alternatively retain with the first notch or the second notch, such that when the elastic locker retains with the first notch, the positioning plate limits the locking seat, and when the elastic locker retains with the second notch, the positioning plate releases the locking seat.