Objective To understand the significance of Silverman anderson score for assessing the severity extent of preterm infants with respiratory distress syndrome (RDS). Methods A total of 130 preterm infants with respiratory distress syndrome were divided into 3 groups according to the Silverman Anderson (SA)score:mild group (3~5 scores),moderate group (6~7 scores) and severite group (8~10 scores).The difference of respiratory rates (RR),heart rates (HR),mean blood pressure (MBP),Fraction of inspired oxygen(FiO₂),the pressure of NCPAP,X-ray grading of RDS,the number of NCPAP success and surporting by endotracheal intubation,SA value of NCPAP success and failure in each group were compared. Results 1)There were statistically significant differences in RR(F=8.990),HR(F=17.792),MBP(F=8.677),FiO₂(F=69.187) and oxygenation index(F=50.807) among the group of the mild,moderate and severite group(all P<0.01).2)There were statistically significant differences in the pressure of NCPAP between the mild and moderate group(F=83.216,P=0.000).The pressure of the mild was higher than that of the moderate group.3)There were statistically significant differences in the X-ray grading of RDS (χ²=33.24),the number of NCPAP success and surporting by endotracheal intubation(χ²=62.62) among the three groups(all P=0.000).4)There was statistically significant differences in the SA value between the NCPAP success and failure(F=13.404,P=0.001). Conclusions SA score can objectively reflect the severity extent of preterm infants with RDS.It might help the clinicians to rapidly assess the severity extent of the infants and give appropriate measures to the infants in the ward.So it might improve the quality of treatment of RDS.