【Abstract】 Objective To investigate the correlation between Fetuses NT’s thickness values and their abnormal pregnancy, and further evaluate measurement of NT’s application in fetal prognosis. Methods 1) Collect the sample of 584 prenatal ultrasonography fetuses with NT thickening observation (3mm in week 11-13+6) from July 2014 to July 2016; 2) Segment the NT cases by different NT values (3.0 -3.9mm, 4.0 -4.9mm, ≥5mm) and calculate the abnormal fetal structural ratio, chromosome abnormalities ratio and poor prognosis incidences in segments; 3) Analyze and test statistically the relationship between fetuses NT thickness and their abnormal pregnancy ratio. Results 1) Ultrasonography finds that 1.85% fetuses have the abnormal NT value (≥3), which turn out to be 56.51% normal and 43.49% abnormal (structural abnormalities all-inclusive) fetuses; 2) The chromosome core type analysis on the 419 fetuses with NT>3 illustrates, 364 turn out to be normal while as high as 55 cases have karyotype abnormalities; 3) Survival comparison analysis on the delivery illustrate: the distribution of the 584 cases with NT≥3 is that normal pregnancy accounts for 283, abortion/intrauterine stopped-growth accounts for 15, induced labor cases account for 282 and follow-up loss cases account for 4; 4) Statistical test results further demonstrate: there is significant difference of abnormal fetal structural ratio (with Chi-square value of 3.464 and according P-value of 0.019) and poor prognosis incidences (with Chi-square value of 37.312 and according P-value of 0.000) among different segments of high NT values. However, there is NO strong correlation statistically between high NT value and chromosome abnormalities ratio. Conclusion NT thickness value has high correlation with abnormal pregnancy ratio and the ratio increases significantly along with the higher NT values. Thus NT thickness values can serve as an effective indicator in prenatal screening.