Objective To study the real-time triggering threshold value manually clinical effect and value of multi-slice spiral CT in lower extremity arteries imaging for clinical basis. Methods January 2015-May 2016 suspected of 70 cases of lower extremity arterial disease patients to hospital for treatment, the patients were divided into different control group of 35 cases and 35 cases of observation group according to the detection method. The control group was triggered manually, until the time density curve to a peak steady manually initiate a scan， real-time observation group threshold value manually triggering threshold to be reached 150Hu delay 6s start scanning, image quality between the two groups. Results The observed cohort, average delay time was significantly shorter than the control group (P<0.05), two groups were the main-iliac vessels, bone-popliteal artery and arteries edge image quality score difference was not statistically significant (P>0.05), the observation group blood vessels below the knee, foot and edge arteries artery image quality score was significantly higher (P<0.05), two groups were common iliac artery, femoral popliteal artery, anterior tibial artery and foot dorsal artery vein interference score was no significant difference (P>0.05). Conclusion Patients with suspected lower extremity arterial disease by real-time triggering threshold value manually over the diagnosis can be delayed scan time and improve the image of lower extremity arteries, should be widely applied.