The preparation method of ultra-thin magnetic spiked nickel foil includes the following steps: Step S1: Prepare the body fluid containing Ni2+ precursor, specifically, mix the aqueous solution of sodium hydroxide glycol with the aqueous solution of Ni2+ glycol, and stir to obtain the pale green solution.

Add hydrazine to water and stir constantly to get a blue solution. Step S2: Load the precursor body fluids containing Ni2+ into the reactor and react at 50℃ ~ 90℃ for 0.5 ~ 2.0h. Step S3: Remove the nickel foil growing on the reactor wall, wash it several times after separation and dry it. 

The preparation process of the invention is simple, non-toxic and pollution-free, and the cost is low, which can meet the requirements of large-scale production. The ultrathin magnetic barbed nickel foil produced by the invention is unsupported, its thickness can be as thin as 0.5 ~ 3.0 m, the size can reach several hundred square centimeters, and has good mechanical properties.