An auto-iris control method, wherein the method comprises: setting a target luminance value of an auto iris (S201, S301); collecting an image at a current moment, and calculating a luminance value of the image collected at the current moment (S202, S302); comparing the target luminance value with the luminance value of the image collected at the current moment, to obtain a difference between them and use it as a luminance difference at the current moment (S203, S303); comparing an absolute value of the luminance difference at the current moment with a preset luminance difference threshold, determining a status of the auto iris at the current moment, and using a corresponding PID algorithm to calculate a direct current control voltage at the current moment (S204, S304-S306); and adjusting an action of the auto iris according to the calculated direct current control voltage (S205, S307); characterized in that comparing an absolute value of the luminance difference at the current moment with a preset luminance difference threshold, determining a status of the auto iris at the current moment, and using a corresponding PID algorithm to calculate a direct current control voltage at the current moment comprises: if the absolute value of the luminance difference at the current moment is greater than the preset luminance difference threshold, using a positional PID algorithm to calculate the direct current control voltage at the current moment; and if the absolute value of the luminance difference at the current moment is less than or equal to the preset luminance difference threshold, using an incremental PID algorithm to calculate the direct current control voltage at the current moment. setting a target luminance value of an auto iris (S201, S301); collecting an image at a current moment, and calculating a luminance value of the image collected at the current moment (S202, S302); comparing the target luminance value with the luminance value of the image collected at the current moment, to obtain a difference between them and use it as a luminance difference at the current moment (S203, S303); comparing an absolute value of the luminance difference at the current moment with a preset luminance difference threshold, determining a status of the auto iris at the current moment, and using a corresponding PID algorithm to calculate a direct current control voltage at the current moment (S204, S304-S306); and adjusting an action of the auto iris according to the calculated direct current control voltage (S205, S307); characterized in that comparing an absolute value of the luminance difference at the current moment with a preset luminance difference threshold, determining a status of the auto iris at the current moment, and using a corresponding PID algorithm to calculate a direct current control voltage at the current moment comprises: if the absolute value of the luminance difference at the current moment is greater than the preset luminance difference threshold, using a positional PID algorithm to calculate the direct current control voltage at the current moment; and if the absolute value of the luminance difference at the current moment is less than or equal to the preset luminance difference threshold, using an incremental PID algorithm to calculate the direct current control voltage at the current moment.