Objective To explore the effect of balloon dilation combined with catheter-directed thrombolysis(CDT)in the treatment of deep venous thrombosis(DVT)of the lower extremities.Methods The clinical data of 41 patients with DVT who received CDT treatment in the department of vascular surgery,Tongling People's Hospital from November 2017 to December 2023 were retrospectively analyzed.According to whether balloon dilatation was used during the operation,the patients were divided into the observation group(balloon dilatation combined with CDT,n=20)and the control group(CDT alone,n=21).The differences in the efficacy of the two groups were evaluated by comparing the amounts of urokinase used,thrombolysis time,hospitalization days,time to peak fibrinogen decline,thrombolysis success rate,thrombus removal time,Villalta score,changes in fibrinogen and venous patency,anddema resolution rate.Results Compared with CDT alone,balloon dilatation combined with CDT had a shorter thrombus removal time[3(1,5)months vs 5(3,8)months],P<0.05.In terms of hospitalization time,urokinase dosage,and thrombolysis time,balloon dilatation combined with CDT were significantly lower than those of CDT alone,P<0.05,and the time to reach the peak decrease in fibrinogen was significantly shorter than that of CDT alone[(15.45±8.14)h vs(21.71±9.95)h,P<0.05].During the observation group,there was a linear relationship between the change of fibrinogen and the venous pa-tency rate.Conclusion The combination of balloon dilation and CDT has better thrombolysis efficiency and lower bleeding risk than CDT alone in the treatment of DVT.