As the waveband granularity of uniform waveband switching is fixed and deficient in flexibility and extensibility

this paper presents a novel multi-granularity optical cross-connection architecture and on the basis of this architecture a Flexible and Extensible Non-uniform waveBand Switching（FENBS）algorithm.When there is a smaller number of path-overlapped traffics

they are grouped into smaller granular wavebands

and when there is a larger number of such traffics

they are grouped into larger granular wavebands so that waveband grouping becomes more flexible than uniform waveband switching

thus enabling more traffics to be contained in the waveband and saving the port.Simulation results show that fewer ports are occupied when the FENBS algorithm is used than when uniform-granularity Balanced Path routing with Heavy Traffic first waveband assignment（BPHT）algorithm is used.