The invention discloses a preparation method of a collagen fiber immobilized tannin loaded nanometer zero-valent Fe-Ni bimetallic ball adsorption reduction material, which comprises the following steps: adding ultrapure water into collagen fibers, soaking overnight, adding tannin, stirring, filtering, dispersing in a crosslinking agent solution, regulating the pH value, crosslinking, filtering, washing, and drying to obtain a collagen fiber cured tannin material; dispersing the collagen fiber cured tannin material in water, adding a Fe < 3 + > solution or a Fe < 2 + > solution, adjusting the pH value, stirring and reacting to obtain a mixed solution, adding a Ni < 2 + > solution into the mixed solution, adjusting the pH value, continuously reacting, filtering and washing; re-dispersing theobtained material in a reducing agent solution, reducing at normal temperature, filtering, washing, repeatedly dehydrating with ethanol, and drying in vacuum to obtain the collagen fiber immobilizedtannin loaded nanometer zero-valent Fe-Ni bimetallic ball adsorption reduction material; the material can be applied to adsorption and separation of various heavy metals, and has ultrahigh adsorptioncapacity for certain metal ions.