The invention discloses a multi-electrode electromagnetic flow meter designing method. The multi-electrode electromagnetic flow meter designing method comprises the following steps of: determining positions and weighting coefficients of each pair of electrodes by a space magnetic field distributed in a measurement tube, and performing iterative operation according to the principle that weighting vector distribution determined by the positions and the weighting coefficients of the electrodes is orthogonal with the vector distribution of the space magnetic field and the weighting coefficients of micro flow rates of fluids in the measurement tube are distributed uniformly; non-uniformly distributing each pair of electrodes on the wall of the measurement tube, and setting the weighting coefficients of each pair of electrodes through a magnification coefficient of a secondary circuit; and transmitting potential difference signals amplified by the secondary circuit and weighted and aggregated to an electromagnetic flow meter converter to realize judgment of average flow rate of the fluids in the tube. The multi-electrode electromagnetic flow meter designing method endows an electromagnetic flow meter with better flow field interference resistance, and can realize the characteristic of precise measurement of asymmetrical flow fields.