The invention discloses a method for treating waste pollutants in a pig farm. The method comprises the following steps of: A, performing anaerobic treatment on a biogas generating pit, namely building the biogas generating pit, performing anaerobic treatment on waste pollutants, which enter the biogas generating pit, in the pig farm, and killing parasites and pathogenic microorganisms through anaerobic fermentation, wherein the chemical oxygen demand (COD) content is reduced, and the normal growth of aquatic plants in a wet land is facilitated; B, performing primary ecological wet land treatment, namely planting green watermifoil, growing the green watermifoil, absorbing nitrogen and phosphorus, harvesting the watermifoil as materials covering a tea yard and a fruit yard; C, treating secondary wet land treatment, namely planting perennial bengal waterdropwort herb in winter, planting aquatic water spinach in summer, and harvesting the water spinach and the perennial bengal waterdropwort herb from the wet land each year; D, treating a tertiary economical wet land, namely planting perennial bengal waterdropwort herb in windter, planting lotus root in summer, putting natural crucians into the wet land, and harvesting the lotus root, the bengal waterdropwort herb and water products from the wet land each year. The construction cost and the running cost are low; the method is easy to operate; the nitrogen, the phosphorus and the COD (Chemical Oxygen Demand) in the waste in the pig farm can be greatly treated; and the method is extremely good in popularization and application prospect.