Objective To explore clinical values of screening Down's syndrome (DS) in pregnant women with mid-term gestation through detecting human chorionic gonadotropin (ß-HCG) combined alpha-fetoprotein (AFP). Methods The serum levels of ß-HCG and AFP in 5058 woman with mid-term gestation of 15-18⁺⁶ weeks were detected by chemiluminescence immunoassay. The corresponding simulation software was used to calculate the risk of fetus with DS, Neural tube defects (NTD) and Trisomy18. Results The positive cases in 5058 cases of pregnant women screened for DS, NTD and 18-three-positive were 141 cases (2.79%); 153 cases (3.02%) and 3 cases (0.06%), respectively. The positive rates in age above 35 trimester prenatal screening of pregnant women were significantly higher than that of age below 35 (P <0.01).  Conclusion It may be a beneficial, effective and convenient of screening DS in mid-gestation through detecting ß-HCG combining AFP.