The invention relates to the technical field of heavy metal soil treatment, and discloses a remediation method for contaminated site soil treatment, which comprises the following steps of: S1, preparing raw materials, contaminated soil, an eluting agent, a flocculating agent, a coagulant aid and an alkaline solution; S2, removing impurities, namely removing garbage in the contaminated soil; S3, crushing, namely carrying out crushing pretreatment on the contaminated soil subjected to impurity removal by utilizing a soil crusher; S4, leaching, firstly, carrying out ex-situ leaching on the contaminated soil with water, and then adding a leaching agent to carry out ex-situ leaching on the soil to obtain a mixed solution; and S5, carrying out solid-liquid separation, namely carrying out solid-liquid separation on the mixed solution, backfilling the soil which is qualified in leaching, and reserving a cleaning solution. According to the method, the leaching method is selected to treat and repair the soil, the leaching method has the characteristics of wide application range, quick effect, large treatment capacity, remarkable effect and the like, and natural citric acid and deionized water are adopted as leaching agents, so that heavy metals in the contaminated soil can be removed, and secondary pollution cannot be caused.