Abstract: The present disclosure discloses a watch strap buckle with a hidden locking device. The watch strap buckle includes a U-shaped snap ring; a rotating shaft is arranged at an open end of the U-shaped snap ring; one end of a buckle tongue is mounted on the rotating shaft, and the other end of the buckle tongue can be inserted into a watch strap hole; first limiting holes for the spring bolt to extend and retract are formed in left and right side surfaces of the box body; second limiting holes for the spring bolts to extend and retract are correspondingly formed in corresponding positions of left and right supports of the snap ring; and the watch strap buckle further includes an independent retraction actuation rod. The watch strap buckle is stable, reliable, convenient and practical.