Multi-mode sequencing batch active sludge sewage treatment method and system

The invention relates to a multi-mode constant-water-level sequencing batch active sludge sewage treatment method and system, belonging to the technical field of sewage treatment. The system comprises a sludge concentration pre-anoxic pond, an anaerobic pond, an anoxic pond, an aerobic pond, a facultative pond and a sequencing batch pond which are communicated, wherein the facultative pond runs in an aerobic or anoxic way. According to the system, multi-mode sewage treatment ways including an anaerobic-anoxic-aerobic mode, an anoxic-anaerobic-aerobic mode and an anaerobic-anoxic-aerobic-anoxic-aerobic mode can be performed. Due to the adoption of the sewage treatment method, the removing effects of nitrogen, phosphorus and organic matters can be enhanced, and equipment utilization ratio is increased.