A charging system for an electric vehicle and a method for controlling charging of an electric vehicle are provided. The charging system comprises: a power battery (10); a charge-discharge socket (20); an external power supply device (1002); a charging connection device (1001); and an energy control device (1003), comprising: a three-level bidirectional DC-AC module (30); a charge-discharge control module (50); and a control module (60) configured to control the charge-discharge control module (50) according to a current working mode of the electric vehicle. The energy control device (1003) and the external power supply device (1002) communicate by transmitting a modulated PWM signal to each other via the charging connection device (1001), and the control module (60) controls the three-level bidirectional DC-AC module (30) and the charge-discharge control module (50) to charge the power battery (10) by the external power supply device (1002).