Abstract: In order to ensure the seismic safety of freestanding equipment in isolated buildings, the floor rocking spectrum of isolated structures is obtained based on the dynamic characteristics of isolated structures and overturning-type equipment, and the interaction between isolated structures and freestanding equipment is also taken into account. Considering the main factors affecting the floor rocking spectrum, the floor rocking spectrum of several isolated structure-freestanding equipment combination systems is statistically analyzed by the orthogonal test method, and the floor design rocking spectrum of the isolated structure is calibrated. A real-time hybrid test system of isolated structure-freestanding equipment combination systems is established and carried out on three different isolated structure-freestanding equipment combination systems to evaluate the accuracy and reliability of the proposed floor design rocking spectrum. The results show that the proposed floor design rocking spectrum is consistent with the floor mean spectrum obtained from the tests, and the average error of the spectrum values at each periodic point is less than 5%, which indicates that the proposed floor design rocking spectrum can restore the curve change of the spectrum, and each characteristic parameter can objectively describe the main characteristics of the spectrum, and the spectrum value is estimated accurately. With this floor design rocking spectrum, for the overturning-type of cabinet freestanding equipment, as long as the equipment appearance size, equipment mass, seismic isolation structure parameters and earthquake parameters are known, the maximum sway angle of the freestanding equipment can be determined, which is convenient for engineering applications.