Abstract: Objective To study the value of screening for Down's Syndrome in the first or/and second trimesters of pregnancy and explore the optimal screening strategy for Down's syndrome. Methods Total of 110 pregnant women were enrolled in this study from March 2014 to November 2015 received measurement of fetal nuchal translucency (NT), and detection of the concentration of maternal serum markers in first-trimester and second-trimester. The high risk rate was assessed according to screening strategies of the first-trimester one-stop screening, the second-trimester triple serum screening and the first-trimester combined with the secondtrimester screening, respectively. Results The total high risk rates were 10.9%(12/110), 9.8%(9/92) and 5.4%(5/92) in the firsttrimester one-stop screening, second-trimester triple serum screening, and the combined test of the first-trimester and secondtrimester screening, respectively. The significant differences were observed between the combined test and the first-trimester one-stop screening or the second-trimester triple serum screening test (χ²=29.54, P< 0.05; χ²=20.65, P< 0.05). Conclusion The high risk rate decreased in the combined test of the first-trimester and the second-trimester triple serum screening, which is of great value in screening for Down's syndrome.