The invention discloses a sewage solid-liquid separation and purification system. The system comprises a sewage transfer pump, a reagent reaction tank, a liquid reagent transfer pump, at least one sewage reaction tank, a mixed solution transfer pump and a solid-liquid separation unit; and the solid-liquid separation unit is provided with a mixed solution inlet, a sludge outlet and a clear outlet, and comprises a centrifuge, a filter screen and a purifying chamber. The sewage solid-liquid separation and purification system realizes accurately-quantified stable and continuous solid-liquid separation and purification of sewage.