Abstract: A replaceable spring arm structure for a spectacles includes an elongated spring arm which has a front end connected to a respective side extension of the spectacles and is detachably disposed in the slider cavity provided on a front end of a temple of the spectacles in a slidably movable manner, a locking member slidably mounted on the spring arm for locking with the locking through hole of the slider cavity so as to securely hold the spring arm in the slider cavity, and a resilient element which is mounted on the spring arm for applying an urging pressure against the spring arm, so as to normally retain the spring arm at an innermost position of the slider cavity. During folding and unfolding the spectacles, the spring arm is driven to slide outwardly along the slider cavity by a pulling force applied by the respective temple, so as to compress the resilient element.