The invention provides an anionic collector. The anionic collector is mainly prepared from, by weight, 25-30 parts of petroleum sodium sulfonate, 20-25 parts of drainage oil, 2-3 parts of triethanolamine, 3-4 parts of dimethyl phthalate, and 35-40 parts of water with the pH value being 10. According to the obtained anionic collector, the two low-cost waste by-products, namely petroleum sodium sulfonate and drainage oil, are used as the main raw materials, so that the cost of the anionic collector is greatly reduced, the phosphorus collection rate is increased, the grade of phosphorus remaining after phosphorus tailings are subjected to floatation through the anionic collector is lowered to an extremely low level, and phosphorus in the tailings is efficiently recovered. According to a preparation method provided by the invention, the raw materials do not need to be separated and purified, reaction products are all used as anionic collectors, no waste is produced, the reaction temperature requirement is low, waste resources are effectively utilized, huge economic benefits can be created, and the anionic collector is applicable to large-scale industrial application.