Acute lower limb ischemia (ALI) with antiphospholipid syndrome (APS) is a potentially fatal disease. We performed retrospective analysis of prospectively collected data from patients examined from January 2015 to January 2021 that were diagnosed with definite APS and ALI, and tested positive for antiphospholipid antibodies; had undergone computed tomographic angiography or color doppler ultrasound, and showed clinical manifestations. In total, 72 APS-ALI patients were enrolled in this cohort study. The patients were divided into two groups: the delayed APS diagnosis group (APS-d) (n=40) and the timely APS diagnosis group (APS-t) (n=32).72.2% patients showed relieved ischemia symptoms (APS-d vs APS-t, p=0.035), 27.8% patients showed recurrence of thrombosis, and 23.6%patients needed further surgery (APS-d vs APS-t, p=0.042). 37.5% APS patients were administered intravenous immunoglobulin (IVIG) (APS-d vs APS-t, p<0.01) and 34.8% were administered hormonotherapy (APS-d vs APS-t, p<0.01). The rate of amputation was 19.4% (APS-d vs APS-t, p=0.049) and the mortality rate was 16.6% (APS-d vs APS-t, p=0.033).Delayed diagnosis of APS in ALI patients was associated with a high risk of amputation and mortality. ALI patients who were diagnosed with APS early and underwent timely initiation of hormonotherapy, IVIG and anticoagulation, showed improved amputation and mortality.