Voltage sags can lead to abnormal operation of electric vehicle charging equipment, but the problem has not been paid more attention now. With the gradual increase in the application of electric vehicles, it is necessary to study the impacts of voltage sags on the electric vehicles charging. The simulation models of 6-pulse rectifier charger, 12-pulse rectifier charger and PWM rectifier charger are established, then the impacts of different severity and different types of voltage sags on chargers working in different conditions are analyzed and the degree of influence is assessed. The simulation results show that the impacts of voltage sags on chargers are not only related to the strength and types of voltage sags, but also related to the working state of the chargers.