The invention discloses an illumination energy-saving control method based on an amplitude-variable Newton extremum searching algorithm. PID closed-loop control is used to meet the illumination requirement, the amplitude-variable Newton extremum searching algorithm is used to carry out iteration continuously to search for a minimal energy consumption value of an illumination system, and stable output in the minimal value is maintained; and a positive signal is introduced into the amplitude-variable Newton extremum searching algorithm so as the change the disturbance amplitude, and a variable is increased rapidly to ensure the accuracy of the algorithm and then reduced to shorten time needed by searching of the algorithm. The method of the invention can improve the speed and accuracy of the Newton extremum searching algorithm, and further the whole performance of the illumination energy-saving control method is improved.