Establishing an integrated energy system (IES) is an effective means to promote the efficient utilization of energy resources. Reasonable planning and design software for IESs can provide tailored design solutions according to engineering needs. However, the lack of multi-scenario-compatible planning software remains a bottleneck for the widespread industrial application of IESs. To address this issue, a comprehensive and highly reliable IES plan (IES-PLAN) design platform has been developed to scientifically guide users in designing reliable, low-carbon, and efficient IESs. The platform offers a graphical interaction interface, allowing users to flexibly set planning scenarios and goals based on their needs. To validate the platform’s effectiveness and practicality, a simulation case study is conducted based on the “Nanjing Hospital IES.” The results demonstrate the platform’s responsiveness and planning performance under different customized requirements, achieving reduced energy costs and improved energy utilization efficiency.