The invention relates to a test system for transient step response of a flexible direct-current electronic voltage transformer, wherein an EVT digital value receiving module is used for receiving a sample signal sent by a merging unit of a tested direct-current electronic voltage transformer, and a signal conditioning loop is used for sending a digital signal of a standard signal; a clock module is respectively used for controlling the standard signal and the sample signal to have an uniform time sequence and time scale; the synchronized standard signal and sample signal are processed by a step high value calculation module and a step low value calculation module; the stable direct current components of the standard signal and sample signal are processed by a 10% time calculation module and a 90% time calculation module; the output values of the 10% time calculation module and 90% time calculation module are input into a step response delay calculation module, and the step response delay calculation module is used for calculating the difference value of the time moments corresponding to the standard signal and the sample signal respectively. The system meets the requirement of flexible direct current transmission on the reliability of the flexible direct-current electronic voltage transformer.