The invention discloses steel for a heat-resistant high-strength sleeve and a preparation process of the steel. The steel consists of the following chemical components in percentage by weight: 0.10-0.25% of C, 0.10-0.30% of Si, 0.70-1.30% of Mn, 0.05-0.30% of Hf, 0.001-0.006% of B, 0-0.20% of Mo, 0-0.25% of W, 0-0.15% of Nb, 0-0.20% of Ta, 0-0.18% of Ti, 0-0.18% of Zr, 0.01-0.20% of RE, not greater than 0.008% of P, not greater than 0.004% of S and the balance of Fe. According to the steel for the heat-resistant high-strength sleeve and the preparation method of the steel, a high-temperature deformation quenching process is adopted for the whole sleeve, so that a relatively high dislocation density and other deformation defects are kept to obtain the sleeve with uniform tissue and high toughness; a medium-temperature section long-time thermal insulation process and a high-temperature section short-time thermal insulation process are adopted, so that relatively high strength is kept and the toughness is remarkably improved; elements such as Nb, W, Hf, Mo, Re and the like are added and quickly cooled to a temperature lower than 260 DEG C to preserve the heat for a long time, so that heat resistance, high strength, high toughness and high impact resistance of the sleeve are effectively guaranteed.