Objective To analyze the medium - and long-term efficacy of simple transcatheter closure in the treatment of children with patent ductus arteriosus (PDA) complicated with moderate and severe mitral regurgitation (MR), and to explore its safety and feasibility. Methods Clinical data of children diagnosed with PDA complicated with moderate and severe MR and treated with transcatheter closure from March 2013 to March 2019 were retrospectively analyzed. Results A total of 121 children (27 boys and 94 girls) with a median age of 19.8 (8.0-28.0) months were included. There were 94 cases with moderate MR and 27 cases with severe MR. Echocardiography showed that the diameter of PDA was (6.4±1.8) mm. There were statistically significant differences in the main pulmonary artery (MPA) diameter, left atrium (LA) diameter, left ventricular end diastolic diameter (LVEDD) and left ventricular end systolic diameter (LVESD) among different time points (preoperative, postoperative 24 h, postoperative 1, 3, 6, 12 and 24 months) (P<0.05). Compared with pre-operation, MPA diameter, LA diameter, LVEDD and LVESD were all shortened at each follow-up time point after surgery, with statistical significance (P<0.05). During the follow-up period, 120 children (93.4%) had less MR than pre-operation. There were statistically significant differences in MR areas of all children among different time points (preoperative, postoperative 24 h, postoperative 1, 3, 6, 12 and 24 months) (P<0.05). The postoperative MR area at each follow-up time point was significantly smaller than that before surgery (P<0.05), but there was no significant difference in MR area between 12 and 24 months after surgery (P>0.05). Conclusions On the premise of strictly grasping the surgical indications, simple transcatheter closure can improve MR degree and reduce left heart load in PDA combined with moderate and severe MR in children, which is safe and effective.