We　propose　a　scheme　for　the　preparation　of　a　spin-qubit　Greenberger-Horne-Zeilinger　(GHZ)　state　and　W　state　by　using　quantum　dots　(QDs)　in　double-sided　optical　microcavities　with　the　help　of　polarized　photons.　The　spin-selective　photon　reflection　from　the　cavity　provides　us　a　perfect　way　to　achieve　the　scheme　by　adding　some　simple　linear　optical　elements　and　conventional　photon　detectors.　A　numerical　simulation　demonstrates　that　a　perfect　scheme　of　the　GHZ　state　and　W　state　generation　can　be　achieved　in　one　step,　and　high　fidelities　can　be　realized　when　the　side　leakage　and　cavity　loss　are　low,　which　is　feasible　in　the　weak　coupling　regime.　Therefore,　our　scheme　might　contribute　to　quantum　communication,　quantum　teleportation,　and　some　other　fields　in　quantum　information　processing.　(C)　2015　Optical　Society　of　America