A new steel-asphalt composite seismic isolation layer is introduced briefly. Based on data of shake table tests, regression analysis by least squares method is adopted to analyze the natural frequency and the damping ratio of a new isolation layer. The calculation results show that the damping increases as the input acceleration increases because when PGA is relatively large, the lateral displacement of the isolation layer is large, the distance between the upper beam and the lower beam become smaller. The upper beam squeezes the asphalt ointment between it and brick piers. Part of the vertical load begins to transfer to the brick piers and friction occurs between brick piers and upper beam.. It is good for displacement limit of the structure.