With the explosive growth of network transmission data, traditional integrated circuit is facing difficulties of further increasing exchange rate and expanding chip capacity. Compared with traditional electronic chips, silicon photonic devices present the advantages of high speed, low power consumption, larger bandwidth, lower cost, good compatibility with CMOS process, thus they show great potentials to meet the requirements of next-generation all-optical switching networks, the optical interconnection for data centers and the high-performance computing. Therefore, silicon photonics is widely recognized as one of the most promising solutions to break through the bottleneck of capacity in the post-Moore era. In this work, technical principles of silicon-based optical switch and switch arrays are introduced, especially MZI and MRR switch units and the construction strategy of switch array. Progresses and proposal of promising solutions to the challenges of silicon optical switches are reviewed.