To study bacterial changes of bile, to detect relationship between formation of core of gallstones and bacterial infection. Floras of bacteria in bile were studied in patients with gallstones by using aerobic, anaerobic and Lforms (X, Y,L) culturing system.Results: Bacterial growth positive was found in 88 of 98 patients in which single bacterial growth accounted for 54 cases, multiple growth 34 including type X 83, type L 23 and type Y 5. The results show that some alteration of bacteria flora exists during biliary infection and S. Liguefaoiens and E. Coli are the most frequent bacteria present. Formation of the core of gallstone might be related with bacterial infection.