Large dimensional bulk 1045 carbon steel with nanolaminate pearlite is prepared by aluminothermic reaction casting method. The steel is rolled at 873 K with different thickness reduction. Microstructures evolution and mechanical properties are characterized in detail. The results show that the nanolaminate cementites are crushed with the increase of thickness reduction, the dislocation density increases, meanwhile the tensile strength is improved greatly. The rolled steels possess the key combination of three characteristics, namely, high density dislocation, nanolamination, and second‐phase particles. When the thickness reduction is 60%, most of the lamellar cementites are crushed to globular particles, the tensile strength reaches 719 MPa, and the elongation is 14%. It provides a guidance for all high strength alloy design efforts by this route.