The invention discloses a system and a method of energy conservation and emission reduction for recycling sewage. The method comprises the following steps: (1) discharging sewage generated from papermaking to a collecting basin; (2) pumping the sewage in the collecting basin into a reaction tank, and adding a cleanser during pumping; (3) discharging the preliminarily purified sewage to a primary storage tank for deposition; (4) after deposition, pumping clear water at the upper layer of the primary storage tank for papermaking; (5) pumping sewage at the lower layer of the primary storage tank into a biochemical pool for a biochemical reaction; (6) recycling mud at the bottom of the primary storage tank as a papermaking raw material; and (7) discharging sewage reacted in the biochemical pool to a secondary sedimentation tank for deposition, pumping clear water after deposition for papermaking, and recycling mud at the bottom of the secondary sedimentation tank as a papermaking raw material. The environmental pollution problem due to papermaking sewage is solved, and recycle of resource is realized.