Objective  Transgenic mice expressing human TAR DNA/RNA binding protein 43 (hTDP-43) mutant protein in spinal cord motor neurons were constructed using HB9 promoter to establish a disease model of amyotrophic lateral sclerosis (ALS) and explore the mechanism of ALS induced by hTDP-43 mutation.    Methods  HB9 promoter junction mutant hTDP-43 vector was constructed in vitro, and the positive transgenic mouse strains were  prepared by prokaryotic injection and screened(There were 8~10 mutations at Q331K and M337V). Gait analysis, rotary rod fatigue test, and suspension test were used to detect locomotion ability of mice. Immunohistochemistry, immunofluorescence staining and Western blotting were used to detect hTDP-43, phosphorylated HTDP-43 (p-hTDP-43), Caspase-3, cleaved Caspase-3, respectively. Expression of ubiquitin, β-tubulinⅢ(Tuj1), Ki67 and cyclin-dependent kinase 5 (CDK5)proteins were also detected.    Results  In transgenic mice expressing mutant hTDP-43 protein in spinal motor neurons, both hind limbs were atrophied to the trunk side, and motor function showed progressive decline with increasing age. hTDP-43, p-hTDP-43, Caspase-3, and cleaved Caspase-3 were observed in spinal motor neurons Caspase-3 positive staining and ubiquitin protein positive inclusion body, and in vitro isolation and culture of spinal motor neurons, it was found that hTDP-43- and ubiquitin protein co-located in choline acetyl translocation enzyme (ChAT）positive motor neurons, accompanied by ectopic expression of CDK5.     Conclusion  The mutant HDP 43 protein expressed in mouse spinal cord motor neurons can promote the re-entry of differentiated mature neurons into the cell cycle, leading to the occurrence of ALS.