This paper clarifies the operating principles of an orthogonal reactor with harmonic suppression, which possesses such advantages as smooth power regulation, low current harmonic content, and fast response. By combining the reactor own harmonic and configuration analysis, an expanded method about suppress its own harmonic and through harmonic calculate reflection to compensate the control harmonic is obtained. According to the feature, the control harmonic is fast getting corresponding output in turn. An automatically regulation system is presented for the power regulation. And the paper also demonstrates the feasibility and effectiveness of this system