The boundaries of the honeycomb-cells are considered to be free and the stresses of the soils at the cavities are zero, the conformal mapping method of complex functions for regular hexagon to circle and expansion method of wave functions are adopted, and then the theoretical solutions are obtained about the isolation problem of incident plane SV waves by the honeycomb-cell barriers. By studying the normalized displacements which are the ratios of the displacements caused by the incident and scattering SV waves to those only by the incident SV waves, the isolation effects of the honeycomb-cell barriers are analyzed, and some important conclusions are drawn out, which are that: (1) the isolation effects of the barriers are better for SV waves with higher frequencies than those with lower frequencies; (2) the areas near the two side edges of the barriers have better isolation effects than the middle; (3) the isolation effects increase with the total length and the row number of the honeycomb-cell barriers; (4) the isolation effects and construction and maintenance costs are considered, and three rows of honeycomb-cell barriers are better selection for vibration isolation design. In the end, vibration isolation effects of three types are compared and the conclusions are that: three rows of honeycomb-cell barriers are between open trench and three rows of cavities and near to open trench.