This paper report a study of three-dimensional(3D)reconstruction and dynamic display for a series of CT images of lumbar vertebral canal.It provides a newresearch method for the spinal column biomechanics.By means of the contour reconstruction we made 3D reconstruction for complete human lumbar vertebra.The reconstructive graphic could be rotated cut and transformed in any orientation.It could realize dynamic display and accurately show the structure and form of lumbar vertebral canal.Based on the 3D image reconstruction,image processing.technique was used to measure the spinal canal effective area(SCEA)after dynamic exchange and get the result of the percentage of effective area.The result showed the dynamic exchange of SCEA was related to the clinical symptom and the therapeutic effect of the lumbar vertebra disease.This method of spinal Canal CT image 3D reconstruction could extend its use into other fields.