This strain is a humanized SMN2 gene model of spinal muscular atrophy (SMA). The endogenous Smn1 gene in mice was replaced with the human SMN2 gene fragment to simulate the pathogenesis of SMA patients in mice. However, since the SMN2 gene mainly produces the SMNΔ7 protein, which lacks exon 7, the humanized SMN2 gene cannot fully compensate for the abnormalities caused by the loss of the Smn1 gene, resulting in an SMA-like phenotype in the model. Due to the correlation between SMA subtypes and SMN2 copy numbers, this model can be mated with Rosa26-hSMN2 mice, which have SMN2 genes inserted in chromosome 6, to increase the copy number of SMN2 in mice and improve the survival period of the model. This can simulate different SMA subtypes, which can be used for more relevant pathogenic mechanisms and preclinical studies of drugs.