The invention discloses a heat treatment technology for an engine shield. The heat treatment technology comprises the steps of 1) carrying out normalizing, specifically, carrying out secondary normalizing treatment on the cast-formed engine shield; 2) carrying out high-temperature
tempering, specifically, carrying out heat preservation on the normalized shield in a furnace at 340-380 DEG C for 6-8 hours, carrying out high-temperature
tempering to increase the temperature to 670-730 DEG C, carrying out heat preservation for 8-10 hours, gradually cooling the shield until the temperature is lower than 120 DEG C, and discharging the shield from the furnace; 3) carrying out
quenching, specifically, raising the temperature of the shield to 680-720 DEG C, carrying out heat preservation for 2-3 hours, increasing the temperature to the
quenching temperature of 820-880 DEG C, carrying out heat preservation for 4-5 hours, and then carrying out
water cooling to the
room temperature; and 4) carrying out annealing, specifically, the shield is finally heated to 380-420 DEG c, carrying out heat preservation for 8-10 hours, increasing the temperature to the annealing temperature of 660-720 DEG C, carrying out heat preservation for 10-12 hours, and carrying out
air cooling to the
room temperature. According to the heat treatment technology, the
heating temperature is properly increased and the heat preservation time is prolonged, and therefore the structure of
alloy steel of the engine shield can be fully converted, the
mechanical property and the
impact toughness of the engine shield can be effectively improved, and the good comprehensive
mechanical property requirements of the automobile engine shield can be met.