Objective To explore the differential diagnostic value of color-Doppler technique in acute and chronic thrombosis of leg arteries. Methods The two-dimensional and color Doppler ultrasonographic characteristics were analyzed in acute thrombostic event in 80 leg arteries and chronic thrombostic events in 244 leg arteries. And some parameters (history, the vessel wall structures, hemodynamic of inlet and outlet at the lesion) were compared, too. Results There existed a significant difference in history, vessel wall structure and the establishment of collaterals between the acute and chronic groups. And there were also significant difference in maximum blood velocity proximal and distal to the lesion and proximal resistant index between two groups(P