Objective To explore the clinical application value of karyotyping and chromosome microarray analysis (CMA) in prenatal diagnosis of fetuses with abnormal ultrasonographic soft markers (USM). Methods A total of 345 singleton pregnant women with abnormal USM but without structural abnormalities who had both karyotyping and CMA testing were selected.Then,the test results and maternal data were analyzed. Results Among the 345 cases of abnormal USM,there were 152 cases with single USM,149 cases with other prenatal diagnosis indications,and 44 cases with multiple USM.The detection rates of pathogenic chromosomal abnormalities were 2.63% (4/152),10.74% (16/149) and 20.45% (9/44),respectively.The difference in detection rates between the three groups was statistically significant (χ²= 15.932,P<0.001).The detection rate of pathogenic chromosomal abnormalities with different USM ranged from 0.00% to 21.43%.The USM with the highest detection rate of pathogenic chromosomal abnormalities was nuchal fold (NF) thickening (21.43%),followed by nasal bone loss/dysplasia (12.68%).In the 345 cases,the detection rate of karyotyping chromosomal abnormalities was 7.27% (25/345),and the detection rate of CMA was 14.53% (50/345).No abnormality was detected by CMA in 4 fetuses with chromosomal abnormality by karyotyping.Among cases with normal karyotypes,29 copy number variation (CNV) were detected by CMA. Conclusion The fetus with NF thickening,nasal bone loss/dysplasia,multiple USM abnormalities or single USM abnormality combined with other prenatal indications have a higher detection rate of pathogenic chromosomal abnormality.Therefore,it is recommended to conduct interventional prenatal diagnosis.The results of karyotyping and CMA can be mutually verified and supplemented to provide a more accurate and effective genetic diagnosis for fetuses with abnormal USM.