As different tiers are stacked together in 3-D integrated circuits, the power/ground (P/G) network simulation becomes more challenging than that of 2-D cases. In this brief, we propose a hierarchical simulation method suitable for 3-D P/G network (HS3-DPG), which takes advantage of the inherent hierarchical structure of 3-D P/G network. The port equivalent model (PEM) is introduced to mask the details of P/G grid in each tier. Besides, we introduce the locality property to further simplify the simulation. Some 3-D P/G network benchmarks extracted from industrial designs are used to verify the correctness of our method. Experimental results show that, HS3-DPG can achieve considerable speedup, while maintaining high accuracy. Simplified PEMs considering the locality property can save nearly 80% memory allocation compared with the full PEMs when the number of through-silicon-vias between the adjacent tiers becomes quite large.