To study the impact of electric vehicle DC chargers on the power grid harmonics, the influence factors of grid harmonics are discussed, according to the national standard.With the observed data of a specific DC charger, the harmonic current is analyzed when the DC chargers were integrated into the power grid.The maximum number of DC chargers is studied, taking the different minimum short circuit capacity and power supply capacity of points of common coupling into account.This work provides theoretical basis for the configuration of electric vehicle DC chargers.