A novel 2×2 optical switch, which consists of phase spatial light modulator (PSLM), polarizing beam-splitter (PBS), mirror, half-wave plate(HWP) and quarter-wave plate (QWP), is proposed. This new kind of configuration of the optical switch has the features of less optical components, compact structure, efficient performance, and insensitiveness to polarization of signal beam. In addition, the straight and the exchange functions of 2×2 optical switch are implemented bi-directionally in free-space. A optical experimental module of polarization-independent 4×4 optical switch is achieved by cascading polarization-independent bidirectional 2×2 optical switch and is analyzed according to path control table. Simultaneously, a kind of polarization-dependent 4×4 optical switch is also investigated for comparison, the exchange sort of the polarization-dependent 4×4 optical switch is achieved by control of polarization state of signal beam for routing.