An optical sight includes an outer barrel unit, an objective lens unit, an ocular lens unit, a magnification unit, amounting unit, and a range-finding module. The outer barrel unit extends about an axis and has a front end and a rear end. The objective lens unit is mounted to the front end of the outer barrel unit. The ocular lens unit is mounted to the rear end of the outer barrel unit. The magnification unit is disposed between the objective lens unit and the ocular lens unit. The mounting unit is disposed in the outer barrel unit between the objective lens unit and the magnification unit, and has an outer peripheral surface, and an inner passage extending along the axis. The range-finding module is disposed in the outer barrel unit, and includes a light emitter, a light receiver, and a circuit board unit.