<正> Based on the principle of fluid mechanics a mathematical model of the oval gallbladder’smoving boundaries was obtained by CT

radio contrast radiography and B mode echography.Weadopted for the first time in this field

the finite element method to calculate the transient flow fieldwithin the human gallbladder in vivo and successfully made out the distribution of bile flow withinthe cyst

known as Newtonian fluid and axisymmetric flow.Thus we completed the poineering ofthe bile flow study within the gallbladder

and confirmed the way of the cholelithogenesis withinthe cyst.Theoretically the vortex flow is proved to be the mechanical factor in the formation ofgallbladder stone and several conclusions were drawn from this study:（1）near the axis of thecontacting gallbladder exists an accelerated bile out-flow column;（2）near the central cross-section ofthe flow field there exist two opposed vortex areas

the one which near the axis rotatescounterwise and flows faster;（3）a gross similarity exists between the law of attenuation of bile flowvelocity and the gallbladder contraction;（4）chololithogenesis within the cyst is related to the vortex inthe flow field.