Abstract: Objective: To investigate the mechanism of attenuad bacillus calmette-guerin(BCG) unite high dose of vitamin A(Vit A) interfered in asthma pneumonia.Methods: All mice were allergized by intraperitoneal injection of ovum albumin(OVA) and two treatment groups were endermic injeced with BCG at 1st day of experiment.The mice of one of treatment groups took orally high dose of vitamin A 100 u after 10 days and other contrasted by NS.All mice atomization OVA were stimulated asthma after experiment.two weeks and were examined with methods pathology,histochemis-try,ELISA.Results: Longer course of severe allergic pneumonia,significant higher IL-13 and TNF-α factors of Th2 reaction in the group of asthma.The mice of group sensitization with OVA and BCG innoculation occurrenced Th1 reaction and Th2 reaction suppressed.Another mice of group with overdose VitA and BCG inoculation aggravated lung lymphoid inflammation.Vit A promoted mononuclear-macrophages shifted into the inflammation site of lung,aggratated alveolitis by oneself lysosomal enzyme release.Down blood plasma IL-13 and TNF-α factors level obviously,and hypolevel IFN-γ.Overdose VitA changed Th1 type induced by BCG inoculation,provocated non-Th1,non-Th2 reaction.Conclusions: BCG unite high dose of vitamin A possible activation lysosomal hydrolase of cell to aggrav pneumonia at acute stage,can provocated non-Th1,non-Th2 reaction and shorten the course of disease.