An intelligent decision-making method for maintaining urban underground sewer network includes steps of: analyzing with a sewer network functional defect three-dimensional instantaneous hydraulic model; calibrating parameters by finite element fitting analysis and full-scale test, and verifying accuracy of the sewer network functional defect three-dimensional instantaneous hydraulic model; combining node water level iteration method, Preissmann slit method, Godunov finite volume method and unstructured grid to rebuild a surface-subsurface one-two-dimensional coupled connection model; using R language, dynamic library linking technology, and long-short-term memory neural network method of multi-source data samples for engineering secondary development of the surface-subsurface one-two-dimensional coupled connection model, and obtaining urban sewer network functional defect conditions with waterlogging result labels; and establishing a multi-objective planning intelligent decision-making model for sewer network maintenance and a solving method thereof. The present invention provides intelligent, accurate and scientific management for urban sewer network.