A ferrofluid bearing with controllable damping effect was designed,which uses the damping controllable mag- netic fluid to replace the pressure oil film in the gap between the inner and outer rings of the ordinary sliding bearing,and the vibration of the bearing can be controlled by adjusting the viscosity damping of the internal ferrofluid with the external magnetic field. A performance test system for the ferrofluid bearing consisting of the servo motor,eddy current sensor and data acquisition system was built to study the vibration of the bearing at different speed and current. The results show that, when applying the external magnetic field,the vibration amplitude of the ferrofluid bearing is significantly reduced. The greater the applied current,the more obvious the suppression effect on the amplitude,which shows that the damping effect of the ferrofluid sliding bearing is obvious and its damping is controllable.