A novel 2×2 optical switch is proposed with conventional polarization controlling technology by using phase spatial-light modulator (PSLM), polarized beam splitter (PBS) and mirror. This new kind optical switch grants the features of less optical components, compact structure, efficient performance, convenient control and function insensitive to polarization of signal beam. In addition, the straight and the exchange functions of 2×2 optical switch are implemented bidirectionally in free-space. Furthermore, a new optical experimental module of 4×4 optical switch is presented by cascading polarization-independent bidirectional 2×2 optical switch. Moreover, the routing state table of 4×4 optical switch to perform all-permutation output and nonblocking switch for the input signal beams, is achieved by choosing and controlling routing. Finally, the function properties and operational process of 4×4 optical switch are discussed in detail.