The special type isolated building defined as asymmetric multi-tower base isolated structure with large floor is discussed in this paper. The rigid layers in series models are obtained and the elastic time history method is used to analyze the performance and seismic response of the structure. With the objective of studying the influence of the mass eccentricity in the towers and the asymmetric towers, coefficients of shear force, the ratios of period and the ratios of drift are discussed. The following conclusions have been attained: Torsional drift can be significant depending on the isolated layer in the asymmetric multi-tower with large floor. Comparing with the fixed base structures, this special type isolated building still can be reduced torsional response. The effect of isolation is reduced with the mass eccentricity in the towers and the asymmetric towers increases. It is concluded from the study that the multi-tower base isolated building with large floor should be symmetric and central in order to increase performance of isolation.