The invention relates to an oily soil remediation agent and a preparation method thereof. The oily soil remediation agent has a gray-black appearance, a pore diameter of 2-30nm, and a pore volume of 1.118×10 ‑3 ‑1.391×10 ‑ 3 cm 3 / g, the specific surface area is 1.021‑1.811m 2 / g, X-ray diffraction spectrometer analyzes that it has diffraction peaks at 29.40°, 35.96°, 39.40°, 43.16°, 47.51°, 48.50°, and infrared spectrum shows that it has a diffraction peak at 2680cm ‑1 , 2516cm ‑1 , 2335cm ‑1 , 1800cm ‑1 , 1445cm ‑1 , 876cm ‑1 , 708cm ‑1 There is an absorption peak. The present invention adopts surfactant freezing infiltration and high-temperature calcination to prepare shells into an oily soil remediation agent, which can effectively absorb and degrade oily soil in the soil, and the removal rate reaches 49.38%, and the seed germination rate and total biomass after repairing reach 100% and 71.08g / m 2 .