An optical fiber cassette with corresponding rail structures includes a plurality of rail structures and an optical fiber cassette. Each rail structure includes a front flexible buckling arm and a rear buckling hook. The front flexible buckling arm includes a first suspended arm reflexed from a front portion of the rail structure and a stopping block formed on an end portion of the first suspended arm. The optical fiber cassette is located between the corresponding rail structures. The optical fiber cassette includes a front engaging block corresponding to the front flexible buckling arm and a rear buckling arm corresponding to the rear buckling hook. The rear flexible buckling arm includes a second suspended arm reflexed from a rear portion of the optical fiber cassette and an engaging hook formed on an end portion of the second suspended arm.