The invention discloses a preparation method of a bearing steel large sample electrolytic sample. The preparation method comprises the steps that a coarse sample is taken from a bearing steel material, the coarse sample is subjected to spheroidizing annealing, and then is smoothened on a lathe or polished, and therefore the sample can be obtained; the spheroidizing annealing process is that the coarse sample is heated to 790-810 DEG C along with a furnace, kept for 3-6 hours at the temperature, then cooled to 650 DEG C or below along with the furnace, and taken out for air cooling. After spheroidizing annealing is adopted in the method, the sample structure is transformed from lamellar pearlite into spherical pearlite, and surface lamellar metal of the sample is effectively prevented fromfalling off in the electrolysis process. According to the bearing steel large sample electrolytic sample prepared by adopting the method, the surface lamellar metal of the sample can be effectively prevented from falling off in the electrolysis process, the experiment result accuracy is improved, and the labor intensity is lowered.