Composite Ni particles each having a silica coat is improved in oxidation resistance and heat shrink characteristics. A method of preparing composite Ni particles by using an organic Ni composite includes steps of: stirring and heating a nickel salt solution and a raw material of silica coat at a temperature ranging 25° C. to 80° C. for 0.5 hours to 2 hours; filtering, cleaning and drying a resultant product into an organic nickel composite; and thermally treating the organic nickel composite at a temperature ranging from 200° C. to 500° C. for 0.5 hours to 4 hours. The resultant composite Ni particles have excellent oxidation resistance and heat shrink characteristics.