A nonmagnetic biomedical implant material is single phase austenite, and comprises 0.6-1.5wt% of C, 13-35wt% of Mn, 0.5-0.6wt% of Si, 0.5-2wt% of Ca, 0.5-2wt% of Zn, 0.5-2wt% of Ag, 0.016-0.020wt% of S, 0.022-0.025wt% of P, and the balance of Fe. A preparation method of the nonmagnetic biomedical implant material comprises the following steps: carrying out three-pass liquid nitrogen cold rolling on the above single phase austenite steel with the press amounts of 10-20%, 8-15% and 2-5% respectively; and carrying out two-stage annealing treatment: heating at a rate of 5-40DEG C/min to 200-300DEG C, carrying out heat insulation for 60-180min, cooling in a furnace, heating at a rate of 30-40DEG C/min to 600-800DEG C, carrying out heat insulation for 20-40min, and cooling in the furnace to prepare the nonmagnetic biomedical implant material. The nonmagnetic biomedical implant material has the advantages of short production period, low cost, and obviously improved integral degradation rate.