<p>High-dimensional multipartite entanglement plays a central role in high-capacity anti-noise quantum communication and quantum computation fields. In the paper, we propose a practical preparation protocol for four-photon three-dimensional spatial-path GHZ state with spontaneous parametric down-conversion (SPDC) sources and non-ideal photon detectors. Our preparation protocol is highly feasible under current experimental conditions. The SPDC source and the non-ideal photon detectors would introduce disturbed items into the output quantum state and reduce the fidelity of the target three-dimensional spatial-path GHZ state to about 0.09. By adopting the quantum non-demolition detection on two of the four output modes, one can eliminate most of the disturbed items and increase the fidelity to about 3/7. Our protocol can provide a theoretical guidance for the experimental preparation of the high-dimensional spatial-path GHZ state and has application potential in future quantum communication and computation field.</p>