Due to the influence of distance variations and parasitic parameters, it is difficult for wireless power transfer (WPT) systems to maintain a controllable constant voltage output. Therefore, it is crucial to add appropriate control strategies to address the issue. Fractional-order devices have attracted attention in the field of power electronics due to their higher degrees of freedom. A passive fractional-order capacitor (P-FOC) has been proposed to clamp the current phase in the WPT system by adjusting its voltage phase angle. In this paper, a fractional-order WPT system based on a P-FOC has been proposed with controllable constant voltage (CV) output. And the soft switching operation can be maintained during the charging process. Meanwhile, the system performance from the perspectives of device stress and power loss has been analyzed. Through verification experiments on a 200W prototype, the results show that by adjusting the phase angle of the proposed P-FOC, the load/distance independent controllable CV output in the proposed WPT system can be achieved. And the optimal efficiency measured under heavy load reached 94.3%. Finally, theoretical analysis and experimental verification have confirmed the feasibility of the proposed scheme.