ObjectiveTo explore the effect of sustained spinal cord compression on spinal cord injury (SCI).MethodsTwenty four dogs underwent sustained spinal cord compression for 30 minutes (group A), 90 minutes (group B) and 180 min (group C) with a device designed by the authors for weight loading spinal compression, and anthor four dogs as the control group (group D) only underwent surgical operation without SCI. Cortex somatosensory evoked potentials (CSEP) were monitored during all the procedure of making model. The changes of pathologic histology, imaging and behavior examination of all animals were observed.ResultsThe lesion degrees gradually increased from group A to group C (P<0.01), and there was similar outcome in MRI imaging. The behavior improvement in group A was more significantly than that in groups B and C (P<0.05).ConclusionSustained spinal cord compression aggravates the extent of SCI process, and the decompression must be taken as soon as possible.