An optical fiber fastening device holds an optical fiber which includes a core and a cladding layer surrounding the core. The cladding layer includes strips peeled from the core. The optical fiber fastening device includes a clamping member and a fastening sleeve. The clamping member includes a first and a second clamping portion buckled together to clamp the optical fiber, with one including at least one locating rod configured for being wrapped around by the strips, and the other including at least one locating hole receiving the at least one locating rod. The fastening sleeve sleeves over and holds the first and the second clamping portion together.