The invention provides a medium- and small-sized sewage treatment integrated device which comprises a biotreatment unit, a precipitate and sludge return unit, an optical catalytic oxidization unit, a deep treatment unit and a disinfection unit sequentially connected, wherein the precipitate and sludge return unit is respectively connected with the water inlet of the optical catalytic oxidization unit and the water inlet and water outlet of the deep treatment unit; the biotreatment unit comprises a water inlet region, an anaerobic treatment region, an anaerobic treatment region and an aerobic treatment region which are sequentially connected; the deep treatment region comprises a water distributing tank, a particle active carbon filter material layer, a quartz sand filter layer and a cobblestone supporting layer which are sequentially connected from top to bottom. The device has the characteristics of being compact in structure, small in occupied area, convenient to use, flexible to operate, low in treatment cost, high in effluent quality, strong in adaptability and the like and has relatively good popularization and application prospects.