Objective To investigate the risk factors of pretermsmall for gestational age (SGA) and appropriate for gestational age (AGA),and to provide basis for clinical intervention in preterm SGA. Methods A total of 1 370 preterm infants admitted to the First Affiliated Hospital of Kunming Medical University from January 2011 to December 2017 were enrolled. The relationship between gestational age and birth weight was divided into SGA group (675 cases) and AGA group (695 cases). The general situation of premature infants in the two groups,perinatal high risk factors and complications were compared. Results 1) Birth weight,birth length,birth head circumference,discharge weight,discharge length of SGA group were less than those of AGA group.Hospitalization days in SGA group were longer than that in AGA group,the difference was statistically significant (χ² =-11.62、-7.12、-5.25、-5.72、-2.1、4.46,P<0.05);2)There were significant differences between SGA group and AGA group in maternal age maternal,pregnancy-induced hypertension syndrome,placental abnormality,cesarean section (t=65.841,170.937,19.558,92.719,P＜0.05); 3) The incidence of asphyxia,neonatal respiratory distress syndrome,myocardial injury,feeding intolerance,pneumonia sepsis,hypoglycemia and hypothyroxinemia in preterm SGA group were signigicantly higher than that in AGA group (t=4.465、4.162、6.035、3.97、5.180、5.21、4.71、5.031,P＜0.05);4) Logistic regression analysis indicated that the mother with gestational hypertension (OR=5.64,95%CI:1.28-16.16),placental abnormality (OR=3.65,95%CI:1.16-7.69),multiple pregnancy (OR=2.89,95%CI:1.05-8.84) were independent risk factors for the occurrence of premature SGA. Conclusion Strengthening pregnancy health care,intrauterine monitoring,timely detection of intrauterine growth retardation,active treatment of pregnant mothers can help reduce the incidence of premature SGA; strengthening the monitoring of premature delivery of SGA can reduce the occurrence of complications.