In recent years, extreme rainfall events have occurred frequently, intensifying urban pluvial flooding. Due to insufficient flood-proof design standards, ground-mounted distribution equipment is highly susceptible to inundation and outages during flood events. To enhance the resilience of distribution systems against pluvial flooding, this paper proposes a differentiated planning method for urban distribution networks based on a two-dimensional (2D) hydrodynamic model. First, the generalized extreme value distribution model is used to estimate the multi-year return-period rainfall using historical rainfall data and geographic information, while the study area is simulated with the 2D hydrodynamic model. Second, the failure probability of ground-mounted distribution equipment is evaluated according to its inundation depth. Typical failure scenarios are then generated and selected by combining the hybrid Monte Carlo sampling method and Shannon’s information entropy. Then, an optimization model for differentiated distribution network planning is formulated by comprehensively considering multiple rainfall return-period scenarios, with the objective of minimizing the sum of elevation investment costs and load-loss costs. The optimal elevation level of each ground-mounted distribution device is determined accordingly. Finally, simulations based on a modified IEEE 33-bus system verify that the proposed optimization model significantly enhances the distribution system’s resilience to pluvial flooding while effectively controlling the investment cost of flood-proof retrofits.