In recent years, reconfigurable optical add drop multiplexers (ROADM) and multiple-dimensions optical cross-connection (OXC), as the essential devices of next-generation dynamic optical networks, have been attracted great interests by research institutions and relevant industry. 1′N wavelength selective switch (WSS) is one of the key components in current and next generation ROADM. However, most WSS modules of the present have the disadvantages of complex optical system, large insertion loss and high crosstalk, as well as the imperfection of the port number and the channels number. So, a high port-count 1×32 WSS based on liquid crystal on silicon (LCoS) technology is demonstrated, which has a flexible- tuning bandwidth. By uploading phase holograms at the corresponding locations on the LCoS device, the system allows a certain wavelength of the entire C-band DWDM channels to be switched from any input port to any output port. Experimental results demonstrate the insertion loss is around 5 dB to 25 dB. The 3 dB bandwidth of signal is 40 GHz at the grid of 100 GHz and the bandwidth is tunable from 50 GHz continuously with the step of 1 GHz. The research can provide the theory and experiment foundation for the development of M×N WSS in the future.