Low frequency vibrations threaten the safe operation of high-rising structures as their height rise. Passive dampers only have good damping effect at the tuning point and have a narrow damping bandwidth. Magnetic fluid provides a new solution to this problem. In this article, a semi-active tuned current controlled damper is proposed by using magnetic fluid as the working fluid. First, the theoretical basis for the inherent frequency is established. The theory shows that the current can change the inherent frequency. Secondly, the damper test system is established to evaluate the tuned damping capability under different excitation. Results show that the damping rate of the semi-active current controlled damper is about 22% , and the damping rate of the tuned liquid rolling ball damper is only about 12. 3% . The damping rate will be less than 10% when the frequency ratio between the tuned liquid rolling ball damper and the controlled structure is greater than 1. 11. The semi-active current controlled damper has good robustness, which can effectively reduce the displacement response of the structure and make up for the shortage of the traditional passive dampers with narrow damping bandwidth.