The invention discloses a nano bioremediation method for high-concentration polycyclic aromatic hydrocarbon contaminated site soil. The method comprises the following steps: adding a carbon nanomaterial and a base fertilizer into the high-concentration polycyclic aromatic hydrocarbon contaminated site soil, uniformly spreading medicago sativa seeds into the contaminated soil, keeping the water content of the soil at 60% of the field water capacity, harvesting plants when medicago sativa grows to a flowering or maturation period, and removing the plants from the contaminated soil. According tothe method, the problems of low removal efficiency, long repair period and the like of a bioremediation technology can be solved; the advantages of the nanotechnology and polycyclic aromatic hydrocarbon pollutant degradation by plant rhizosphere are fully exerted; the remediation efficiency is improved, the remediation period is shortened, operation is easy, secondary pollution cannot be caused inthe remediation process, disturbance to soil is small, the economic cost is low, and thus efficient, environment-friendly, economical and sustainable remediation of the site contaminated soil is achieved, and the method has wide application prospects in the field of remediation of the high-concentration polycyclic aromatic hydrocarbon contaminated soil.