Objective To explore the feasibility of coelocentesis in prenatal diagnosis.Methods Coelocentesis were applied on 58 women scheduled for at 6～12 weeks of gestation,and fetal heart rate before the procedure and 1,5,30 minutes afterwards and hemorrhage of amnionic cyst was observed.Y gene of sex-determining region was detected by polymerase chain reaction,and compared with chorionic villi sample.Results The total achievement ratio of coelocentesis was 96.6% of all cases in five minutes.The coelomic fluid was successfully aspirated at first attempt in 93.2% at 7～10 week's gestation,25.0% at 6～7weeks and 50.0% at 10 ~ 12 weeks.There was no significant difference in FHR between before coelocentesis and afterwards (P＞0.05).The detection accurate rate of SRY was 91.1%,all female fetus were matched with those observation by chorionic villi sampling,and only 5 male fetus were not matched,the accurate rate was 80.8%.Conclusion Coclocentesis has the advantage of simple procedure,safe and high feasibility.The optimal time of coclocentesis is in the 7th to 10th week of gestation.