During the past 30 years, many studies on the lumbar spinal biomechanics have been associated with the low back pain problems. In order to enhance the knowledge of the colleagues of the physical therapists, this paper reviewed many literatures related to the lumbar spinal biomechanics and their clinical significance. From the biomechanics point of view, this paper reported the mechanical function, the range of motion, the loadings, and the injury mechanism of the lumbar spine. In the end, the authors also suggested some possible future research directions of the lumbar spinal biomechanics in the field of physical therapy.