Objective:To investigate and compare the efficacy and safety of percutaneous mechanical thrombectomy (PMT) combined with catheter directed thrombolysis and catheter directed thrombolysis alone in the treatment of acute lower extremity deep venous thrombosis.Methods:Retrospective analysis of clinical data of 69 patients with acute lower extremity deep venous thrombosis who met the inclusion criteria of this study from January 2018 to December 2018 in department of vascular surgery, People′s Hospital of Xinjiang Uygur Autonomous Region was performed. There were 35 males and 34 females, with an average age of 59 years and an age rang of 20 to 80 years. Patients were divided into PMT combined catheter directed thrombolysis treated group ( n=38) and catheter directed thrombolysis treated group ( n=31) according to different methods of intra-luminal thrombolysis. The thrombolysis time, dosage of urokinase, thrombotic clearance rate, perimeter difference of suffered limb, and total number of adverse events during perioperative period between two groups were recorded. At 1 month, 3 months, and 6 months after discharge, patients underwent an ultrasonographic examination of lower extremity vessels to check and evaluate residual thrombolysis and thrombosis recurrence by outpatient review. The quantitative data in the two groups were expressed as mean±standard deviation( Mean± SD), t test was used for comparison between groups. Enumeration data in the two groups were expressed as percentage (%) and χ2 test was used for comparison between groups. Results:The thrombolysis time of PMT combined catheter directed thrombolysis treated group and catheter directed thrombolysis treated group were (3.7±2.1) d and (5.2±2.1) d, respectively. The differences between the two groups were statistically significant ( P=0.005). The dosage of urokinase were respectively (225.0±122.3)×10 4 units and (315.8±108.6)×10 4 units, the differences were statistically significant ( P=0.001). PMTⅠ, Ⅱ, Ⅲ thrombus clearance rate in patients with PMT combined catheter directed thrombolysis treated group were 18.4% (7/38), 73.7% (28/38), 7.9% (3/38), while 16.1% (5/31), 77.4% (24/31), 6.5% (2/31) were observed in patients with catheter directed thrombolysis treated group, with no statistically significant difference between the two groups ( P= 0.803, P=0.720, P=0.818). After a period of 48h thrombolytic therapy, the cross-section diameters of suffered thigh and calf were (2.16±0.87) cm and (1.38±0.66) cm in PMT combined catheter directed thrombolysis treated group respectively. While the cross-section diameters of suffered thigh and calf were (1.21±0.59) cm and (1.02±0.49) cm in catheter directed thrombolysis treated group respectively. The differences in the cross-section diameters of suffered thigh and calf were statistically significant after a period of 48h thrombolytic therapy ( P<0.001, P=0.014). Three cases (7.89%) had occurred adverse events during perioperative period in PMT combined catheter directed thrombolysis treated group, while there were 4 cases (12.90%) in catheter directed thrombolysis treated group, with no statistically significant difference between two groups ( P=0.692). The six month follow-up rate of PMT combined with catheter directed thrombolysis treated group was 71.05%(27/38), while that of the catheter directed thrombolysis treated group was 64.52% (20/31), with no statistically significant difierence between the two groups ( P=0.532). During the six month of follow-up, the recurrence rate of thrombus in PMT combined catheter directed thrombolysis treated group (3/27, 11.11%) was lower than those patients in catheter directed thrombolysis treated group (3/20, 15.00%), with no statistically significant difference between the two groups ( P=0.693). Conclusions:Compared with catheter directed thrombolysis treated group, PMT combined catheter directed thrombolysis treated group has a similar clinical efficacy for treatment of acute lower extremity deep venous thrombosis. PMT combined catheter directed thrombolysis treated group has advantages of reducing dosage of urokinase, shortening duration of thrombolysis time and relieving the swelling of suffered limb in a short time rather than catheter directed thrombolysis treated group. It shows a great result in the short term follow up.