An automatic sewage treatment system, comprising an automatic sewage treatment device and a biological carrier, wherein the automatic sewage treatment device comprises a housing; one side of the housing is provided with a sewage inlet, and the other side thereof is provided with a sewage outlet; the sewage inlet is installed on one side of a No. 1 biochemical pool; one side of the No. 1 biochemical pool is connected to a No. 2 biochemical pool through a connecting pipe; the other side of the No. 2 biochemical pool is connected to a No. 3 biochemical pool through the connecting pipe; the other side of the No. 3 biochemical pool is connected to a No. 1 filter mechanism through the connecting pipe; the other side of the No. 1 filter mechanism is connected to a No. 2 filter mechanism through the connecting pipe; the housing wall of one side of the No. 2 filter mechanism is provided with the sewage outlet; the bottom of the No. 2 filter mechanism, the No. 1 filter mechanism, the No. 3 biochemical pool, the No. 2 biochemical pool, and the No. 1 biochemical pool are equipped with microporous aeration pipes; the microporous aeration pipes are connected to an aerator through gas pipelines; the aerator is installed on the top of the housing; one side of the aerator is connected with a distribution box; the upper part of the No. 2 filter mechanism, the No. 1 filter mechanism, the No. 3 biochemical pool, the No. 2 biochemical pool, and the No. 1 biochemical pool are provided with a manhole cover; one side of the manhole cover is provided with a gas valve, and the other side thereof is provided with a detection hole; the biological carrier includes a mobile microorganism carrier and a fixed microorganism carrier; the No. 3 biochemical pool, the No. 2 biochemical pool, and the No. 1 biochemical pool are provided with the mobile microorganism carrier; characterized in that the No. 2 filter mechanism and the No. 1 filter mechanism are equipped with a porous partition; the upper part of the porous partition is provided with the mobile microorganism carrier, and the lower part thereof is provided with the fixed microorganism carrier; the porous partition is drilled with a plurality of through holes. the bottom of the No. 2 filter mechanism, the No. 1 filter mechanism, the No. 3 biochemical pool, the No. 2 biochemical pool, and the No. 1 biochemical pool are equipped with microporous aeration pipes; the microporous aeration pipes are connected to an aerator through gas pipelines; the aerator is installed on the top of the housing; one side of the aerator is connected with a distribution box; the upper part of the No. 2 filter mechanism, the No. 1 filter mechanism, the No. 3 biochemical pool, the No. 2 biochemical pool, and the No. 1 biochemical pool are provided with a manhole cover; one side of the manhole cover is provided with a gas valve, and the other side thereof is provided with a detection hole; the biological carrier includes a mobile microorganism carrier and a fixed microorganism carrier; the No. 3 biochemical pool, the No. 2 biochemical pool, and the No. 1 biochemical pool are provided with the mobile microorganism carrier; characterized in that the No. 2 filter mechanism and the No. 1 filter mechanism are equipped with a porous partition; the upper part of the porous partition is provided with the mobile microorganism carrier, and the lower part thereof is provided with the fixed microorganism carrier; the porous partition is drilled with a plurality of through holes.