Abstract: On observing the cremaster muscle microcirculation blood flow of rats in vivo, the quantitative analyses of the cell-free plasma layer thickness and blood yelocity in arteriole blood flow are carried out with multiple microscope videoimage system and Microcirculation Image Processing(MICP) system.The determination of the plasma layer thickness,central cell column diameter and vessel diameter are made with the microvessel light intensity self-adaptable discernment method,and the RBCs velocity is determined with flying spots method.Upon measurement of the cremaster muscle microvascular flow of control period,bleeding period,shock and recovery period in vivo,the nonlinear regression coresponding curvee and their experimental relationship between the edge.plasma layer and pseudo shear rate are figured out according to experimental data.The critical shear rate value is got as soon as theshock happened.This parameter can be regarded as a new evaluation index of microcirculation barrier.It is specially indicated that the decreasing speed of the thickness of edge plasma layer is greater than that of shear rate,which is the important theology factor that caused the microcirculation barrier in the process of shock microcirculation expanse.