According to the demand of harmonic suppression and reactive power compensation for large-power electrical AC/DC power converter systems， this paper presents a kind of new auto-inductive and harmonic-suppression（AIHS） transformer and a corresponding inductive filtering technology. The general model and harmonic model constructed by the transformer windings and the full-tuned circuit at the specific harmonic frequencies are proposed， and the harmonic equivalent circuit model is established. Based on this， the filtering mechanism of the new inductive filtering technology is revealed， and the necessary impedance condition for the new transformer and the tuned condition for the full-tuned circuit to suppress the main harmonic currents in the secondary windings are obtained. The analytical method of the sensitivity function is applied to analyze the influence of the impedance parameters on the inductive filtering effect. Finally， the test results verify the correctness of theoretical analysis， and present the good inductive filtering performance that the new transformer has.