A rearrangeable nonblocking 8×8 thermo-optic waveguide switch matrix is designed and fabricated on silicon on insulator（SOI）wafer.General multi-mode interferometers（MMI）and Mach-Zehnder interferometer（MZI）are used to construct 2×2 switch cell.The device presents a fast response time of about 2μs.The power consumption of each switch cell is less than 240mW.The extinction ratios vary from 17dB to 22dB.The power consumption and the response times are much better than that of silica-based or polymer-based switch matrix.