Soilbag， with the advantages of high bearing capacity， high damping ratio and low cost， is a kind of base isolation materi? al which is suitable for the low- and mid-rise buildings. The relationship between shear stress-shear strain， dynamic characteristic parameters and shear strength of stacked soilbags were analyzed and discussed through a series of laboratory cyclic simple shear tests. The variation of dynamic shear modulus and equivalent damping ratio of stacked soilbags under different vertical stresses and shear strain amplitude was further investigated. And the influence of number of load cycles on the dynamic characteristic parameters and shear strength parameters was also studied. The test results show that the peak shear stress and dynamic shear modulus in? crease while the equivalent damping ratio decreases with the increasing number of load cycles under small-strain condition； when the shear strain is large enough， the interface slippage and the strain softening occur on stacked soilbags. The peak shear stress （shear strength） decreases with the increasing number of load cycles. And the variation of dynamic characteristic parameters is to? tally opposite to that under small-strain condition. The internal friction angle of the shear strength parameters of stacked soilbags gradually decreases with the increasing number of load cycles while the additional cohesion force increases and tends to be stable during the test. The energy is dissipated through the shear deformation of soil particles inside bags and the interlayer slippage of stacked soilbags under high shear strain amplitude.