Embodiments of the present invention provide a reconfigurable optical add/drop multiplexer, including: an input component, an output component, a beamsplitter, a first switch array, a wavelength dispersion system, a redirection system, and a second switch array. The input component includes M+P input ports, the output component includes N output ports, the beamsplitter is configured to: receive M input beams from M input ports, and split each of the M input beams into at least N parts, to obtain at least M×N beams; the first switch array includes at least P switch units; and the second switch array includes N rows of switch units. The first switch array, the beamsplitter, the wavelength dispersion system, the redirection system, and the second switch array are arranged so that P optical add beams and sub-beams of M×N beams in the at least M×N beams can be routed to the N output ports.