A ferromagnetic element no-load characteristic low-frequency measuring method mainly comprises the following steps: 1) establishing a high-voltage side open-circuit equivalent circuit according to a T-type equivalent circuit, applying two low-frequency sine waves having different frequencies at the low-voltage side, and calculating iron-core loss under each frequency; 2) calculating unit hysteresis and eddy-current loss We and Wh produced in each period, and calculating iron core loss PCoren when converted to the power frequency; 3) calculating exciting current Iexn, harmonic content K(k) and exciting voltage Un when converted to the power frequency according to an eddy current compensation algorithm; 4) calculating no-load loss Pn; and 5) drawing PCoren-Un, Iexn-Un relation curves and a K(k)-Un harmonic content table. The test is carried out by adopting low-frequency power to replace power frequency power, so that test power source capacity can be reduced by times, the size and weight of the test device are reduced, and the test cost is allowed to be lower.