The invention discloses a converter transformer symmetrical voltage boosting no-load test circuit. The converter transformer symmetrical voltage boosting no-load test circuit comprises a variable-frequency power supply cabinet, an excitation transformer T1 and an excitation transformer T2 which are of the same structure, three-order harmonic filters, five-order harmonic filters, a converter transformer, a voltage transformer TV and a current transformer TA; one three-order harmonic filter and one five-order harmonic filter are connected in parallel between an A end and a B end as well as between a C end and a D end respectively; a grid-side bushing of the converter transformer is suspended; two ends of a valve-side bushing of the converter transformer are respectively connected with the A end and the C end; the primary winding of the current transformer TA is connected in series with the A end or on a connecting line between the C end and the valve-side bushing of the converter transformer; and two ends of the primary winding of the voltage transformer TV are respectively connected with the A end and the C end. According to the converter transformer symmetrical voltage boosting no-load test circuit of the invention, the three-order harmonic filters and the five-order harmonic filters are adopted to effectively filter out harmonic generated in the converter transformer in a no-load test, and the excitation transformers and the capacity of a variable-frequency power supply can be effectively used.