The invention provides a process for the heat treatment of a 200 MW or below large-scale rotor, which adopts a cooling mode of water quenching and oil cooling, controls quenching temperature and tempering temperature and strictly controls the oil entry temperature of effluent. A, a rotor is suspended in a furnace, and the temperature is raised to be 350 DEG C and kept constant for 4 hours and then raised to be 650 DEG C and kept constant for 6 hours; B, heat-preservation quenching is performed according to 1h/100mm, during quenching, and the rotor is first cooled in water according to 8 to 12 min/100mm, then enters oil to be cooled according to 15 to 18 min/100mm and finally is taken out from oil; C, after quenching, the rotor is cooled to be below 200 DEG C, and placed back into the furnace for tempering; and D, during tempering cooling, cooling speed is controlled to be less than or equal to 25 DEG C/h, and the highest temperature of the hearth is reduced to be less than or equal to 150 DEG C. The large-scale rotor processed by the process has extremely high strength and excellent plasticity, toughness, and high thermal resistance. The process solves the problem of low rotor performance, avoids cracking risks and guarantees the performance, strength index and impact resistance value of the rotor.