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以126 kV模块化多断口直流真空断路器为研究对象，在连续过渡模型建模中考虑金属蒸气与离子密度的影响，给出中频真空电弧介质恢复动态数学模型；通过对其开断过程的数值仿真，得到断口间鞘层动态变化与介质恢复强度变化关系曲线以及弧后电流、瞬态恢复电压与新阴极表面电场强度分布。采用对比分析方法，研究各断口间瞬态恢复电压分配规律以及弧后介质恢复强度影响因素。研究结果表明：由于线路阻抗产生的瞬态恢复电压等因素使得各断口间开断电压及电弧能量分配不均，某一断口所受电压及电弧能量高于其他断口，金属蒸气初始密度大且弧后电流下降率较大，瞬态恢复电压上升速率更快，鞘层发展速度缓慢，新阴极表面场强较高，易发生重击穿从而导致断路器开断失败。在换流回路中采用较大电容以保证TRV合理分配，进而提高多断口直流真空断路器开断性能。“,”For the 126kV DC vacuum circuit breakers (VCBs) with multi-breaks, the continuous transition model, metal vapor and ion density were introduced to describe the dynamic mathematical model of dielectric recovery with intermediate frequency vacuum arcs. During the breaking process, the numerical simulation was employed to obtain the thickness of the sheath and the curves of the dielectric recovery strength. Based on the numerical simulation, the relationship between the dynamic variation of the sheath and dielectric recovery was obtained. And the statistics can help to analyze the current, transient recovery voltage, electric field strength and dielectric recovery characteristics on the new cathode surface. By comparative analysis, the distribution of transient recovery voltage (TRV) and the factors affecting the dielectric recovery strength could be achieved. The simulation results show that: due to the line impedancebetween the breaks, the voltage and arc energy distribution of each break is not uniform, and the voltage and arc energy distribution on the break are higher than that of the other breaks, the metal vapor has a high initial density, the drop rate of the post-arc current is larger, the rate of TRV is higher and the development speed of sheath is slower. The surface electric field strength on the new cathode is higher. It could initiate re-strike and approach to breaking failure for the whole CB. And larger capacitor is preferred to ensure the reasonable distribution of TRV and improve the breaking probability of DC VCBs with multi-breaks.