An optical fiber fixing device for fixing optical fibers in an optical connector includes a supporting arm, two connecting arms, and a pressing arm. The supporting arm includes a first end and an opposite second end. The connecting arms respectively extend from the first end and the second end toward a same direction. The connecting arms are configured for insertion into the optical connector. The pressing arm extends from the supporting arm between the connecting arms. The pressing arm is configured for pressing the optical fibers onto the optical connector.