Objective To explore segmantal blood pressure ratio in Doppler ultrasound in the evaluation of distal outlets in lower extremity atherosclerosis ocllusion patients undergoing blood vessel prosthesis and provide references to surgical indications. Methods A review research was made on 166 lower extremity atherosclerosis ocllusion patients receiving blood vessel prosthesis therapy in Anzhen hospital in 1998--2005. We analyzed related factors including segmantal blood pressure ratio to potency rate, evaluated the difference of segmantal blood pressure ratio between groups in which the blood vessel prosthesis was patent and that it was not. Results The difference of segmantal blood pressure ratio of outlet is one of the highest risk among risk factors. The Mean ± SDs of segmantal blood pressure ratio of outlet in patent and obstructed groups were 0. 12±0. 09 and 0. 24±0. 14 respectively. The difference of segmantal blood pressure ratio of outlet has a significant difference between the two groups ( P = 0. 001 ). The corresponding 95% confidence interval of patent group is (0,0. 27). Conclusion Doppler ultrasound is a quantitative testing method. The confidence interval of the difference of segmantal blood pressure ratio could be used as the primary reference standard for the assessment of the outlet and to expect the potency rate before the vascular surgical procedures.