The invention relates to a rapid quenching and tempering method of a steering knuckle casted by using low-carbon low-alloy steel. The method comprises the following steps: setting a quenching heating temperature at AC3 + 90-110DEG C, tapping off a casting after the surface temperature of the casting in a measuring furnace of a temperature measurer reaches the quenching heating temperature, quenching, rising a tempering heating temperature to a value 20-30DEG C higher than a present tempering heating temperature, shortening a tempering insulation time to be a value being 1/2-1/3 of a present tempering insulation time when the surface temperature of the casting reaches the tempering heating temperature, carrying out tempering heat insulation, and cooling. The method has the advantages of high quenching and tempering heating temperatures, short heat insulation time, shortened production period, improved production efficiency and reduced energy consumption.