The invention relates to the technical field of sewage treatment and in particular to a sewage treatment system and a sewage treatment method for separating solid-phase pollutants in sewage. The sewage treatment system comprises a sewage treatment tank, wherein a sewage precipitation cavity is formed inside the sewage treatment tank; a precipitate collection cavity is partitioned in the lower partof the sewage precipitation cavity; a pull box which can be pulled out from the right side of the precipitate collection cavity is arranged inside the precipitate collection cavity; a precipitate cleaning frame which can be pulled out from the opening in the right side of the pull box is arranged inside the pull box; a water draining device body is also arranged at the sewage treatment tank; thewater draining device body comprises a sewage draining dreg removal device; the sewage draining dreg removal device comprises a sewage draining dreg removing screening cylinder; a sewage draining slagremoving filtering screen is rotationally arranged inside the sewage draining dreg removing screening cylinder. The sewage treatment method is achieved through the sewage treatment system. By adopting the sewage treatment system and the sewage treatment method, solid pollutants in sewage can be filtered off stage by stage when the sewage is fed in and discharged out.