The invention relates to an ultra-high-toughness nickel containing nanoscale bainite steel and a preparation method thereof. The technical scheme adopted by the invention is that the preparation method comprises the following steps: heating a steel billet to 1250-1300 DEG C, preserving heat for 1-2 hours, rolling at the temperature higher than Ar3 temperature, wherein the final rolling temperatureis 880-920 DEG C, and performing air cooling to room temperature; heating to 880-920 DEG C at the rate of 5-8 DEG C/min, and preserving heat for 30-60 min; and then performing water cooling to 200-230 deg c, preserving heat for 30-35 hours, and performing air cooling to room temperature, thereby preparing the ultra-high-toughness nickel containing nanoscale bainite steel. The steel billet comprises the following chemical components: 0.78-0.83 wt% of C, 1.55-1.65 wt% of Si, 1.96-2.06 wt% of Mn, 0.295-0.305 wt% of Mo, 0.98-1.02 wt% of Cr, 0.98-1.02 wt% of Ni, 0.98-1.02 wt% of Al, 1.482-1.502 wt% of Co, less than 0.008 wt% of P, less than 0.002 wt% of S, less than 0.004 wt% of N, and the balance of Fe and inevitable impurities. The process is simple, large-scale industrial production is realized, and the product prepared according to the preparation method is excellent in mechanical property.