The present invention discloses an online pulverized coal concentration measurement algorithm for primary air based on the electrostatic method. Charge and voltage conversion is performed on a collected electrostatic signal, and then filtering and amplification are performed on the converted electrostatic signal; after signal processing, when the cross-correlation algorithm is used to obtain the maximum correlation coefficient, both the time difference between two electrostatic probes and the distance between two electrostatic rods are fixed, so that the speed of the primary air is obtained; an effective value of the electrostatic signal is related to a pulverized coal concentration and a pulverized coal speed, the effective value of the electrostatic signal is measurable, and after the speed is measured by using the cross-correlation method, the relative concentration of pulverized coal is obtained. The algorithm provided by the present invention has high measurement accuracy, and accurate, reliable and stable measurement results; and the algorithm can be used to guide the adjustment and optimization of a combustion optimization system to optimize a combustion effect of the boiler, so that the coal consumption is reduced, the energy is saved and the emission is reduced.