The invention belongs to the technical field of sewage treatment, and relates to a parallel anaerobic-anoxic-oxic (A2O)-membrane bioreactor (MBR) denitrifying phosphorus removal method. Adopted devices comprise an oxic tank, an anaerobic tank, an anoxic tank and a membrane tank, wherein the oxic tank is connected in parallel with the anaerobic tank; sewage to be treated and external reflux sludge are mixed in a distribution well and flow into the oxic tank and the anaerobic tank according to a proper proportion respectively, and internal reflux mixed liquid which reflows from the anoxic tank also flows into the oxic tank simultaneously; sewage which flows out of the oxic tank and sewage which flows out of the anaerobic tank are mixed and flow into the anoxic tank together for denitrifying phosphorus removal; and the sewage enters an MBR tank for sludge and water separation, and a part of residual sludge serves as the external reflux sludge to be fed into the distribution well. The parallel A2O-MBR denitrifying phosphorus removal method can be used for the new construction and modification engineering of a biological denitrifying phosphorus removal sewage plant, the volume and the aeration amount of an aeration tank can be reduced, and a secondary sedimentation tank can be eliminated simultaneously, so that the floor space of an urban sewage plant is reduced.