The invention belongs to the technical field of wastewater treatment, and discloses a novel MAP-SBR method for treating biogas digester effluent of a pig farm through a phosphorus source. The method comprises the steps that wastewater is introduced into an MAP treatment pool for pre-aeration treatment, and then a fermentation phosphatic fertilizer and a magnesium sulfate precipitant are put into the wastewater; alkaline liquor is added into the MAP treatment pool, the pH of mixed liquor in the pool is adjusted, after aeration, standing is conducted for precipitation, a precipitate is discharged to a precipitate drying pool through the lower portion of the MAP treatment pool for dehydration and drying to obtain phosphatic fertilizer containing nitrogen and magnesium, after treatment, clearwastewater liquor is pumped into an SBR biochemical treatment pool, the aeration stopping ratio and hydraulic retention time in the SBR biochemical treatment pool are controlled, after an SBR reactionis carried out, the COD content in water reaches the standard, and then the biogas digester effluent of the pig farm is treated. By means of the method, a carbon source can be provided for subsequentSBR treatment while ammonia nitrogen is lowered, the process treatment efficiency is high, the recycling degree is high, the treatment capacity can be flexibly adjusted, the operation can be automatically controlled, and a large amount of labor can be saved.