Background Although brachytherapy is one of the most effective ways to treat metastatic spinal tumor with little damage to surrounding healthy tissue, it may cause radiation myelopathy if an overdose occurs. Establishing a valuable animal model can help to find a method to overcome its complications. In the current study, we set up a banna mini-pig model to mimic percutaneous vertebroplasty with 125I seed implantation. Methods Percutaneous vertebroplasty (PVP) combined with interstitial implantation of 125I seeds, 125I seeds were transplanted into the vertebral body at the T13 level of the spine in banna mini-pigs. After raising them for up to eight months, the spinal cord and vertebral body were collected for pathological analysis. Results A potential animal model had been successfully established, no case of radiation myelopathy was found in any of the treated banna pigs, and no significant cellular impairment was noted by pathological analysis. Conclusions It proves that PVP with 125I brachytherapy is an effective method to treat metastasis spinal tumor, and that the banna mini-pig can be a suitable model to investigate the mechanism of brachytherapy complications.