【Abstract】 Objective To evaluate the right ventricular systolic function and influencing factors in patients with atrial septal defect (ASD) by single cardiac cycle realtime threedimensional echocardiography (sRT3DE). Methods In 45 cases of ASD and 45 cases of normal control group, we used twodimensional echocardiography to measure right ventricular enddiastolic diameter (RVd) and right ventricular area change scores (RVFAC), and use sRT3DE measure right ventricular enddiastolic volume (RVEDV), at the end of the right ventricular systolic volume (RVESV), right ventricular stroke volume (RVSV), right ventricular ejection fraction (RVEF). We compared the difference of the right ventricular systolic function parameters among ASD preoperation, ASD postoperation and normal control group, and analysis correlation between RVEF and ASD size, RVEDV, RVESV, RVSV,RVFAC respectively. Results ASD preoperation was the largest and control group was the smallest in RVd, RVEDV, RVESV and RVSV with significant differences (P＜ 001). control group was the largest and ASD preoperation was the smallest in RVFAC and RVEF with significant difference (P＜ 001). Before ASD treatment, RVEF was negatively correlated with ASD size, RVEDV, RVESV (r=0439,0310,0688, P＜ 005), and no correlation with RVSV (P＞0 005). RVEF was positively correlated with FAC (r=0853, P＜ 005). Conclusion sRT3DE can accurately evaluate the right ventricular systolic function before and after ASD treatment, and the right ventricular systolic function of ASD has a good correlation with RVESV.