We present a functional and patient-specific lumbar phantom for the training of spinal durotomy and dura closure under microscopic view, consisting of a lumbar model, pressurized dural surrogate, together immersed in a tissue-mimicking layer simulating fat, muscle and skin. The lumbar model was derived from a patient computed tomography scan, preserving the natural shape and curvature of the lumbar column. The inclusion of the simulated soft-tissue layer was critical for preserving the surgical ergonomics and presented a realistic view under the surgical microscope. As the success of dura repair is indicated by the watertight closure of the thecal sac, the dura surrogate was connected to a pressurized and closed-loop water system to provide functional cerebrospinal fluid leakage during durotomy. This functional phantom is inexpensive to construct, provides a realistic tactile and visual environment for spinal durotomy repair, and can be easily extended to simulate other patient-specific spinal interventions.