The invention discloses a genetically modified mouse construction method of a salivary gland specific expression multi-copy anthropogenic nerve growth factor (NGF) gene. The genetically modified mouse construction method comprises the following steps: connecting 5-6 h NGF genes in series and cloning the 5-6 h NGF genes to the rear of a promoter of a KLK 1 B 22 gene of a mouse, cloning the promoter of the KLK 1 B 22 gene of the mouse from a bacterial artificial chromosome (BAC) or a genome, adopting about 2 kilo base-pairs sequence before an antithymocyte globulin (ATG) gene, cutting off a fragment between a release 1 and a release 2 in the region of the promoter of the KLK 1 B 22 gene of the mouse from a carrier, the fragment between the release 1 and the release2 comprises the promoter of the KLK 1 B 22 gene and the 5-6 h NGF genes, purifying the cut the fragment of the h NGF gene, and injecting the purified fragment of the h NGF gene into a fertilized egg cell nucleus of the mouse in order to generate a genetically modified mouse with the salivary gland specific expression multi-copy anthropogenic NGF gene.