Background: To improve the detection rate of chromosome abnormalities in fetuses and to reduce the birth defects rate in elderly pregnant women using chromosome karyotype analysis combined with the chromosome microarray analysis (CMA) technique. Methods: Overall, 210 elderly pregnant women with singleton pregnancies aged between 16 and 30 weeks (mean gestational age, 19.19 weeks) and 35 and 47 years (mean age, 38.08 years) were selected from January 1, 2020 to June 1, 2021 in the Eugenics Genetics Department of Yulin Maternal and Child Health Hospital. Chromosome G banding karyotype analysis and CMA detection were performed simultaneously. Results: Among the 210 elderly pregnant women with singleton pregnancies, 26 (12.38%) and 52 (24.76%) cases were detected as abnormal using chromosome karyotype analysis and CMA technology, respectively. The abnormal CMA chromosomes’ total detection rate was 12.38% higher than that using chromosome karyotype analysis (p 0.001). CMA detected 22 pathogenic copy number variants (CNVs), 1 probable CNV, and 7 CNVs of unknown clinical significance in patients with normal karyotype analysis. Among the patients with abnormal karyotype analysis, CMA missed detection in 5 cases. Overall, 57 abnormal cases were detected when the two methods were combined, with a detection rate of 27.14% (57/210) higher than that of CMA or karyotype analysis alone. Conclusions: For the prenatal diagnosis of fetal amniotic fluid in elderly pregnant women, the combined application of chromosome karyotype analysis and CMA detection technology can further improve the detection rate of abnormal chromosomes and reduce missed diagnosis rates.