The invention provides a heavy metal polluted soil remediation agent, and a preparation method and an application thereof, and relates to the field of heavy metal polluted soil remediation. Treatmentof heavy metal pollution in soil includes engineering treatment, chemical treatment and plant ecological restoration, and has the disadvantages of low remediation efficiency, high treatment cost, secondary pollution to soil, structural damage of the soil, and loss of some elements in the soil. The heavy metal polluted soil remediation agent provided to overcome the disadvantages in the prior art comprises, by mass, 25-35 parts of zeolite powder, 20-30 parts of montmorillonite powder, 35-45 parts of attapulgite, 10-15 parts of diatomite, 80-100 parts of rice hull powder, 1-8 parts of chitosan,1-10 parts of citric acid, 0.5-2 parts of zinc sulfide, 0.5-2.5 parts of selenium powder and 1-3 parts of negative ion powder. The heavy metal polluted soil remediation agent can effectively convert lead, cadmium, mercury, arsenic, chromium and other heavy metals in the soil through an ion exchange method to achieve the purpose of soil remediation, and has the advantages of easily available raw materials, low cost, and realization of factory mass production.