Objective To explore the application value of noninvasive DNA detection in abnormal soft index of single ultrasound.Methods A total of 600 pregnant women with single ultrasound positive soft index in Heze Maternal and Child Health and Family Planning Service Center from March 12, 2017 to April 20, 2020 were selected as the research objects.The results of induced labor or live birth were used as the gold standard for diagnosis, and non-invasive DNA screening and pregnancy outcome were analyzed.Results Of the 600 pregnant women with positive ultrasonographic soft index, 12 were found to be high risk fetuses by non-invasive DNA examination.By amniotic fluid karyotype analysis, 8 cases were diagnosed with trisomy 21 syndrome, 1 case with trisomy 18 syndrome, 1 case with trisomy 13 syndrome, 1 case with abnormal chromosome number and 1 case with no abnormal karyotype.The sensitivity, specificity,accuracy, misdiagnosis rate and missed diagnosis rate of noninvasive prenatal DNA testing were 84.62%, 99.83%,99.50%, 0.17% and 15.38%, respectively.Patients diagnosed with trisomy 18, trisomy 13, and trisomy 21 with abnormal karyotypes eventually underwent labor induction.One pregnant woman with abnormal number of XYY chromosome chose to deliver at term.Conclusion Non-invasive DNA technology can detect fetal chromosomal abnormalities as early as possible, and has a high accuracy in fetal screening, which is conducive to reducing the risk of abortion and improving the birth quality of population, it is worth popularizing.