The invention discloses a human body implant material with the surface plated with nanocarbon crystal film and a preparation method of the human body implant material with the surface plated with nanocarbon crystal film. The human body implant material is obtained in the manner that by the adoption of a gradient transition layer technology, titanium is used as the transition layer element, and thegradient transition layer is introduced between the hard nanocarbon crystal film and soft metal magnesium. According to the human body implant material with the surface plated with the nanocarbon crystal film, through a quenching heat treatment technology, the metallographic phase structure in the magnesium alloy is changed, so that the hardness of the magnesium alloy is improved; through quenching heat treatment, crystal grains in the magnesium alloy are refined and more evenly distributed, and the corrosion resistance is improved by a certain extent; titanium carbide is used as the transition layer, the titanium carbide has good wear resistance and high hardness, strength and rigidity and also has excellent crack resistance capacity, and stress concentration is not prone to happen. Meanwhile, due to introducing of the titanium element, stress relief is promoted, and meanwhile the stability of non-crystalline carbon film can also be improved.