An optical fiber fixing device includes a base, first fixing block and a second fixing block. The base includes an upper surface has a receiving groove and a groove which is connected with the receiving groove. The receiving groove receives an optical fiber connector, the optical fiber connector receives a plurality of optical fibers, and two ends of the optical fibers separately protrude out of the optical fiber connector. The groove has an optical detecting device, the detecting device defines a plurality of light apertures. The first fixing block is set on the upper surface, which is configured to fix the optical fiber connector into the receiving groove. The second fixing block is received in the groove, in order to fix the detecting device in the groove, the plurality of light apertures are aligned with the plurality of optical fibers.