A method for producing core-shell magnetic alloy nanoparticle, comprising: step 1, dissolving nickel compound to produce solution; step 2, adding surfactant into the solution; step 3, dissolving the first reducing agent to produce the first reducing solution; step 4, adding the first reducing solution into the solution obtained from step 2, obtaining nickel nano-collosol by stirring and aging; step 5, adding metallic compound into the nickel nano-collosol; step 6, dissolving the second reducing agent to produce the second reducing solution; step 7, adding the second reducing solution into the mixed solution obtained from step 5; step 8, allow the product to stand, then discarding the supernatant, redispersing in water or absolute ethyl alcohol to obtain the core-shell magnetic alloy nanoparticle using nickel as the core.