To solve high energy loss in the vacuum preloading drainage system，we propose an energy-storage vacuum preloading system and probe into the drainage consolidation and energy-saving efficiency via vacuum preloading experiments with a single drainage board. It is found that the volume of the vacuum chamber has some influence on the vacuum consolidation efficiency，and the influence on the surface layer is greater than that on the deep layer. The consolidation efficiency of the proposed vacuum preloading system has little difference from that of the conventional one. The energy consumption of the vacuum system is closely related to the vacuum chamber volume. For the vacuum pump with a power of 1.5 kW and a pumping rate of 7.2 m3/h，when the volume ratio of the vacuum chamber and pore in the soil is about 3‰，the energy consumption of the proposed system would be reduced by 50%. The larger the vacuum chamber volume is，the higher the energy-saving efficiency would be. This study can provide theoretical support for the reduction of high energy loss in the vacuum preloading system.