The invention relates to the technical field of materials, and specifically discloses a stainless steel polishing agent and a preparation method thereof. A kind of stainless steel polishing agent, by weight, its preparation raw material comprises at least, abrasive material 8-15 parts, corrosive acid 10-18 parts, oxidizing agent 1-4 parts, lubricant 3-6 parts, surfactant 2-5 parts , 45‑60 parts of water. Compared with the traditional polishing process, the polishing time can be greatly shortened. In addition, the polishing liquid prepared by the invention not only has a high polishing removal rate, but also can make the stainless steel material higher in quality and smoother. The preparation method of the polishing liquid is simple, the cost is low, the polishing process is easy to control, the productivity is high, the product quality is stable, and the invention has great development potential.