The fuzzy domain of traditional fuzzy control is fixed，and the control efficiency will decrease when the dynamic characteristics of the controlled structure or external excitation changes. On the basis of traditional fuzzy control algorithms，a variable universe fuzzy control is designed. The variable universe fuzzy control takes the error and error rate of the controlled structure as input，and the scaling factor as output，achieving adaptive adjustment of the fuzzy domain of the main fuzzy controller. A two-story steel frame structure with a magnetorheological damper as the control device was constructed，and the variable universe fuzzy control system with the displacement and velocity of the first floor as inputs was developed in the dSPACE real-time simulation system. Shaking table tests under different intensities of seismic motion and different additional mass conditions were conducted. The results show that variable universe fuzzy control can adaptively adjust the fuzzy domain，effectively reducing structural displacement，velocity，and acceleration response. When the added mass of the controlled structure and the peak ground acceleration change，the control effect of variable universe fuzzy control is better than that of fuzzy control and OFF passive control.