BPI is a pluripotent protein located in neutrophils and tissue that likely plays a vital role in host defense against GNB (gram-negative bacteria) and their endotoxin by means of its antibiotic and endotoxin neutralizing and disposing functions. BPI has several biological functions in mammals such as human, bovine, pig and rabbit, it also has major influence in the natural defense of the animal body. In this paper, by comparative study on BPI gene expression in various tissues between Rongchang pig and Landrace, we confirmed the expression of pig BPI gene in various tissues to determine the difference expression of antibacterial related gene among indigenous breed (Rongchang pig) and artificially cultivated breed (Landrace), The Rongchang pig (0 day old, 28 day old, 120 day old) and Landrace BPI (0 day old, 28 day old, 120 day old) gene were expressed in normal liver, heart, lung, kidney, spleen and small intestine. The results showed that: The expression level of BPI in lung of Rongchang pig was relatively higher level compared to that in heart, liver, kidney, spleen and small intestine. The expression level of BPI in liver of Landrace was relatively higher level compared to that in heart, lung, kidney, spleen and small intestine. Real-time fluorescence quantitative PCR analysis revealed that the native breed (Rongchang pig) has a better resistance to disease than Landrace. When Rongchang pig and Landrace were 0 day old, the expression level of BPI of Rongchang pig was higher than Landrace in heart, liver, spleen, kidney, small intestine, lower than Landrace in lung. When Rongchang pig and Landrace were 28 day old, the expression level of BPI of Rongchang pig was higher than Landrace in spleen (p<0.05), kidney (p<0.05), small intestine (p<0.05); lower than Landrace in lung, heart, liver. When Rongchang pig and Landrace were 120 day old, the expression level of BPI of Rongchang pig was higher than Landrace in spleen, lung (p<0.05), kidney (p<0.05), small intestine (p<0.05); lower than Landrace in heart, liver. The research trials showed that the expression of BPI gene increased with its increasing age in different growth stages. Ages and tissues are the main factors that influence the gene expression significantly.