The high incidence of L5 nerve root injury is one of the main concerns and challenges in the treatment of high-grade spondylolisthesis(HS). It has been reported in the literature that the essence of L5 nerve root injury after HS surgery is traction injury, and the amount of traction tension is related to the pathological changes of HS, the mechanical properties of nerve root, the degree of reduction, the reconstruction of intervertebral height and the correction of kyphosis，however, it is not clear how much tension causes nerve root damage. The advantage of multimodal intra-operative monitoring in the surgical treatment of severe spondylolisthesis remains uncertain. Therefore, from the perspective of reducing the L5 nerve root injury, the partial reduction of HS may be safer and more reasonable.