This paper reports a case of prenatal diagnosis of fetal Xp22.31 duplication. The pregnant woman underwent amniocentesis at 23 W+3 d for high-throughput CNV seq and karyotype analysis of fetal amniotic fluid cells. The results of fetal CNV seq indicated that there was 1.68 Mb microduplication in Xp22.31, and the karyotype results were normal. After reasonable prenatal consultation, the decision was made to induce labor. Through the discussion of relevant literature, we can provide reference for prenatal counseling of pregnant women。