The invention relates to the technical field of evaluation on quality of electric power and particularly relates to a multi-harmonic-limit multi-period distribution method for a public grid. The method comprises the steps: (1) dividing users into users with relatively high fluctuation and users with relatively low fluctuation; (2) carrying out a harmonic limit distribution method while taking simultaneity factor into account; (3) carrying out a multi-harmonic-limit distribution method for the users with relatively low fluctuation; (4) carrying out a multi-harmonic-limit multi-period distribution method for the users with relatively high fluctuation. According to the method, on the premise of guaranteeing safe and reliable operation of power grids and the users, characteristics of the users of different harmonic sources are comprehensively considered; on the basis of dividing sizes of fluctuation of the users, load peaks and troughs of the public grid are taken into account, the limit to harmonic limit values is refined, and the multi-harmonic-limit multi-period distribution method for the public grid is provided, so that the harmonic limits of the public grid are more fairly and equitably distributed, and the reasonable evaluation on harmonics of the public grid is achieved.