In order to establish an avian original cells infection model of the avian adenovirus type 4,and investigate the pathogenicity of the cell culture viruses to chicken,five serotype 4 avian adenovirus isolated in our laboratory from 2014 to 2017 were inoculated into the LMH cells and transmitted blindly,and supernatants of the LMH cell cultures of each virus were selected and injected into the 4weekold SPF chickens through the leg muscle at a certain dose. The incidence of experimental animals was recorded,the organs of the diseased or dead chickens were collected and pathological sections were made. The histopathological changes of SPF chickens infected by virus were observed and analyzed. The results showed that specific cytopathic effect caused by the group I avian adenovirus began to appear when 5 strains of serotype 4 avian adenovirus were blindly transmitted into the LMH cells. The viral nucleic acid was extracted from the culture and identified by PCR,and a specific amplification fragment of about 564 bp was amplified,indicating that the virus can proliferate stably in the LMH cells. Supernatants of the 10th generation cell culture of each virus were selected for SPF chicken regression test. The results showed that from the 3rd day after the 4weekold SPF chickens were infected,some chickens began to depressed,lost their appetite,became paralyzed and died quickly. Observations of the pathological examination and pathological sections showed that the LMH passaged viruses of HB1,HB2,HB3 and SD1 maintained the pathogenicity to the 4weekold SPF chickens. Typical histopathological changes were observed in the sick and dead chickens,while there were no clinical symptoms and pathological changes in the control group. These results suggest that the LMH cells can be used for the proliferation and passage of avian adenovirus,and it is an ideal cell model for study of the molecular pathogenesis of avian adenovirus. 