Abstract: Evolution of a double-layer gas cylinder induced by a planar shock wave was investigated experimentally and numerically. Three double-layer gas cylinders were generated based on the soap film technology. By fixing the radii of the inner and outer gas cylinders, and changing the position of the inner gas cylinder in the stream-wise direction, the eccentric effect on the double-layer gas cylinder evolution has been highlighted. The results show that when the inner gas cylinder is positioned upstream, a 'jet' toward the upstream interface of the outer cylinder is generated at the late stage. When the inner gas cylinder is positioned downstream, the coupling effect between two downstream interfaces occurs earlier. The linear velocities of the upstream interfaces of the inner and outer gas cylinders are obtained. It is found that the pressures inhibit and promote the upstream interfaces of the inner and outer gas cylinders respectively, and the pressure magnitude is closely related to the position of the inner cylinder. The rarefaction wave impact changes the movement behaviour of the upstream interface of the outer cylinder, and the linear phase will be prolonged or shortened. The outer gas cylinder width is promoted when the eccentricity exists, and its height gradually decreases as the inner one approaches downstream initially. When the inner gas cylinder is positioned upstream, the inner cylinder width is inhibited but its height changes little. The interfacial area and mean volume fraction of the double-layer gas cylinder were extracted from computations, and the results show that the mixing between gases will be promoted when the inner gas cylinder is positioned upstream. Finally, the time-variation of the circulation is obtained. It is found that the circulation of the double-layer gas cylinder at the early stage can be well predicted by the linear superposition of the existing models.