Objective To evaluate the incidence and severity of pulmonary embolism (PE) in patients with different leg deep vein thrombosis (DVT) by computed tomography pulmonary angiography (CTPA).Methods A total of 145 cases who had been confirmed DVT and undergone CTPA were retrospectively analyzed.The DVTs were divided into left side DVT,right side DVT,and bilateral lower DVT groups.The incidence of PE was compared among different groups.CT obstruction index (CTI) was used to estimate the severity of pulmonary artery obstruction.DVT/PEs with CTI were compared among different groups.Results The incidence of PE of the bilateral lower DVT group was 71.4％,which was higher than that in left side DVT group (39.2％).However,no significant difference was found between bilateral lower DVT group and right side DVT group (52.9％) (P ＞ 0.05).The CTI of the bilateral lower DVT (30.20±14.20)％ was higher than that of the left side DVT (19.26 ± 14.02)％ and the right side DVT (18.56 ±11.79) ％ (P ＜ 0.05).Conclusions The bilateral lower DVT was more likely complicated with PE than the left side DVT,the severity of pulmonary artery obstruction of the bilateral lower DVT with PE patient was higher than that of single side DVT with PE patient.