Abstract: Objective To analyze the causes of unqualified blood sample in neonatal screening, and to provide basis for improving the qualification rate of blood sample and adopting intervention measures. Method A total of 96 unqualified blood samples returned by the neonatal disease screening center in Zhejiang province from January 2015 to December 2017 were analyzed.Results In the three years, 96 unqualified blood samples were detected. The detection rate was 0.13% and there was an increasing trend during the three years (χ_trend²=27.775, P=0.000). Among the 96 unqualified blood samples, there were 36 contaminated blood samples, 29 incomplete penetration blood samples and 13 spotting solidification blood samples, respectively. The detection rate of unqualified blood samples in the township hospitals was 0.37%. It was higher than that of the other medical units (χ²=37.573, P=0.000). The detection rate of unqualified blood samples in the private hospitals was 0.46%. It was higher than that of the public hospitals (χ²=18.260, P=0.000). The detection rate of unqualified blood samples in the units with no more than 1500 persons was 0.23%. It was higher than that of the units with more than 1500 persons (χ²=9.502, P=0.002).Conclusion Stabling the neonatal screening team, strengthening the professional training and regulating technical operation are the key measures to ensure the quality of neonatal blood screening.