Objective To provide the anatomical basis for detecting distal outflow tract in late atherosclerosis obliteration in lower extremities.Methods Ten lower extremities that were amputated above knees because of late atherosclerosis obliteration were used in this experiment.The blood vessels in the residual bodies were perfused to run blood vessel cast mould to observe the anatomical and pathological change of the popliteal artery,the anterior and posterior tibial arteries and their collateral vessels.The number and distribution of those collateral vessels were also observed.Results The popliteal artery,anterior and posterior tibial arteries were all occluded due to atherosclerosis.However,there were three types of those collateral arteries:① Atheromatous plaque in bole stretched into collateral arteries and led to occlusion.② Obliteration was only observed at the initial segment,with no obstruction at the distal end but extenuated.③ The collateral arteries originated from the bole artery symmetrically,keeping communicative with each other through punctiform interspaces.The last two types were mainly distributed at the inferior segment of popliteal artery,the superior segment of anterior and posterior tibial arteries,forming vascular anastomosing network in the whole cnemis muscle group.Conclusion Un-obstructed collateral arteries in certain places can be still found,though atherosclerosis obliteration is formed in popliteal artery,anterior and posterior tibial arteries in lower extremities.Therefore,it may be possible to construct collateral outflow tracts if endo-membrane stripping operation is performed.