To compare the results of intramedullary transplantation of olfactory ensheathing cells (OECs) in the repair of spinal cord injury (SCI) in patients at multiple clinical centers, and to explore the standardized transplantation procedures that suit clinical needs. Methods: The results of representative clinical centers were collected and analyzed. Parameters including the concentration of cells, total number of cells, choice of incision, site of transplantation, number of transplantation sites, advantages and disadvantages of transplantation equipment, and postoperative management were compared to clarify impact on clinical outcomes. Results: Four clinical cases were compared in this study: two Chinese centers, one Australian center, and one European center; all cases employed intraspinal intramedullary intraspinal transplantation for the treatment of chronic complete SCI. Cell implantation into the spinal cord parenchyma had certain effect on recovery in chronic complete SCI. Concise surgery appeared to be more suitable for clinical application than precise and complex injection procedures. An excessively large total volume of injection, long procedure time, and large number of cell transplant injection points are possible reasons for suboptimal results of surgery. Sufficient rehabilitation training after transplantation is necessary. Conclusion: Cell implantation into the spinal cord parenchyma is effective for recovery of neurological function in chronic complete SCI patients. Concise surgery appears to be more suitable for clinical application than precise and complex injection procedures, but improper procedures may lead to ineffective results. Sufficient rehabilitation training post-surgery is necessary for the integration of motor recovery.