The invention relates to an unleaded Cu-based sliding bearing material and a preparation method thereof and the invention has the characteristics that: the material is composed of nickel, tin, zinc, iron, graphite, bismuth, copper and assistants, the substrate of the material is unleaded copper alloy, and the antifriction and antisticking constituent element is bismuth and graphite. The Cu-based bearing material features high intensity, and good antifriction and antisticking, thus realizing an unleaded Cu-based bearing material. The lead is cancelled in an original bearing material with lead and copper, and a synergistic effect of bismuth and graphite can replace the use of lead, thus completely overcoming the defect of lead pollution; moreover, the service performance of the bearing remains nearly the same, therefore the unleaded Cu-based sliding bearing material can completely replace the bearing material with lead and copper. The material of the invention can be applied in food machinery, drugs machinery, construction machinery, automobile and other products, and has advantages of good antifriction and antisticking, good heat dissipation effect, oxidation resistance and corrosive resistance.