By introducing the current development and problems of arc-suppression coils， a novel automatic tuning arc-suppression coil based on the theory of transformer with controllable current source load is proposed， which has the properties of linear reactance tuning capacity and little harmonics pollution. Its principle is that the equivalent reactance of the transformer’s primary winding can be regulated by controlling the current of the transformer’s secondary winding， which can be implemented via a voltage source PWM inverter. Moreover， a large capacity apparatus can be realized with the multiple secondary windings structure adopted. The paper analyzes the principle of this new approach and presents the whole control system. The experimental results of an 800 kVA pilot apparatus have proved the validity of the theory as well as the feasibility of the scheme proposed.