The present disclosure relates to a method and apparatus for prolonging a continuous operation period of a methanol-to-olefins water washing process. The method may perform micro cyclone treatment on methanol-to-olefins washing water. The method may also deliver the washing water subjected to micro cyclone treatment and oil removal to a fluidized bed separator for treatment. The method may also adjust the backwash flow to release the intercepted catalyst powder and empty the dirt holding capacity of a pore. The method may also perform three-phase separation on a gas-liquid-solid mixture subjected to backwash, returning the obtained filter media to a particle bed layer, and respectively discharging a backwashing liquid a backwashing gas which comprise a catalyst. The method may also switch the fluidized bed separator to a normal working state, completing the active regeneration of the particle bed layer, and continuing to operate.