The invention relates to a next-door thermal coupling distillation method and equipment for producing polycrystalline silicon. The equipment comprises a low-pressure next-door rectifying tower, a medium-pressure next-door rectifying tower, a high-pressure next-door rectifying tower, a top tower condenser and a tower kettle reboiler, condensation reboilers are arranged between the two rectifying towers, rear tower top gas phase materials release heat in the condensation reboilers and are condensed into cold fluids to return to a rear tower, and front tower kettle materials absorb heat in the condensation reboilers and return to a front tower after becoming reboiling vapor. Coarse trichlorosilane materials are separated though the three next-door rectifying towers successively, low-boiling-point substances are removed at tower tops, high-boiling-point substances are removed at tower bottoms, and high-purity trichlorosilane products are extracted on the lateral line of the high-pressure tower finally. Compared with traditional distillation processes, a next-door distillation technology and a differential-pressure thermal coupling technology can decrease energy consumption and equipment investment. The next-door thermal coupling distillation method and equipment for producing polycrystalline silicon utilizes the next-door distillation technology and the differential-pressure thermal coupling technology simultaneously, the production cost and the energy consumption are decreased greatly, and distillation energy is saved by about 70%.