Objective To establish a refined model of trunk composed of different lumbar segments, lumped thoracic spine and pelvis, analyze the kinematic differences between patients with lumbar disc herniation (LDH) and healthy people during three daily activities, and to compare the refined trunk model with the simplified trunk model adopting the whole lumbar segment, and discuss the necessity of using the refined trunk model for kinematic analysis of LDH patients. Methods Motion capture system NDI was used to collect kinematic parameters of each segment from 15 healthy people and 7 male LDH patients during level walking, trunk flexion and contralateral pickup, then the kinematic differences between patients and healthy people by the two models were compared respectively. Results During level walking, the rotation of the thoracic segment and pelvis for LDH patients increased, while no significant change was found in motion angle of the whole lumbar segment, and the rotation angle of L4-5 segment significantly reduced. During trunk flexion, the flexion angles of all lumbar segments for LDH patients were reduced by varying degrees, and the flexion angle of L3-4 segment was significantly different from that of healthy people. During contralateral pickup, the performance on the sagittal plane was similar to that during flexion. However, the lateral bending angles of L3-4 segment and L4-5 segment for LDH patients were significantly lower than those for healthy people. ConclusionsLDH patients mainly restrict the motion of injured lumbar segments in daily activities. During some motions, only refined model can discover the abnormal motion of injured lumbar segments. Therefore, it is necessary to subdivide the lumbar spine into 5 independent segments for analyzing the kinematic characteristics of LDH patients.