Controllable impedance type superconducting fault current limiter（SFCL） is a novel type of fault current limiter（FCL） which consists of an air-core superconducting transformer and a pulse-width modulation（PWM） converter. In normal state， the output current of PWM converter will be adjusted to ensure that the primary voltage of the transformer is compensated to zero. As a result， the SFCL has no influence on the main circuit. In the case of short circuit， the current-limiting impedance in series with main circuit can be changed by adjusting PWM converter's output current in the amplitude and phase angle， to suppress the fault current. In order to investigate the validity of this FCL and the feasibility of air-core superconducting transformer， a small prototype system is tested. Experimental results are consistent with principle analysis， which is valuable for the further research of installing this type SFCL into actual electric power system.