The invention discloses a device for verifying a non-gateway metering generator outlet voltage transformer. The device comprises a standard voltage transformer. The device is characterized in that the primary side of the standard voltage transformer is connected with the primary side of a measured generator outlet voltage transformer. The secondary side of the standard voltage transformer is cascaded with a voltage ratio standard phase of which the transformation ratio is adjustable. The secondary side of the measured generator outlet voltage transformer is respectively connected with a transformer tester and a voltage load box. The voltage ratio standard phase is connected with the transformer tester. The standard voltage transformer is cascaded with the voltage ratio standard phase of which the transformation ratio is adjustable so that error testing of all the generator outlet voltage transformers of which the voltage level is in the range of 10kV-25kV and secondary voltage is 100V can be realized, error of the generator outlet voltage transformer can be accurately and conveniently verified without frequent replacement of equipment, and the verification efficiency of the generator outlet voltage transformer can be enhanced.