The invention discloses a heavy metal contaminated soil degradation harmless treatment method which comprises the following steps: S1, detecting and analyzing heavy metal contaminated soil, and determining the dosage of a heavy metal contaminated soil degradation repairing agent; S2, preparing the heavy metal contaminated soil degradation repairing agent; S3, leaching; S4, applying the heavy metal contaminated soil degradation repairing agent, and performing ploughing and mixing; S5, planting plants which are suitable for local growth and have enrichment capacity; and S6, detecting until the heavy metal content in the soil reaches the safety standard. Harmless treatment of the heavy metal contaminated soil is achieved, and the requirements of resource utilization, soil replacement and landfill are met; the technology application range is wide, and the method is suitable for remediation of various soils contaminated byheavy metals,including chromium, hexavalent chromium, lead, zinc, copper, chromium, nickel, mercury, arsenic and the like; the technical operation is simple and convenient, the repairing time is short, the capacity increase is less, secondary pollution is avoided, and the cost is lower; and the resource utilization of the polluted soil can be realized, and the repaired soil is suitable for various purposes.