Objective:To investigate the relationship between gene polymorphisms of IGFⅠ,IGFⅡ and birth weight. Methods:In the case-control study,88 small for gestational age infants(SGA),477 appropriate for gestational age infants (AGA) and 265 large for gestational age infants(LGA) were chosen in Nanjing. All the neonates were genotyped for genetic polymorphisms in the IGFⅠ rs35767 and IGFⅡ rs3741205 by using a polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) assay. Linear regression models were used to estimate the association of the genetic polymorphism with LGA and SGA. Results:TT and CT/TT genotype of IGFⅠ rs35767 reduced the risk of SGA significantly(P = 0.024,P = 0.031),the polymorphism in IGFⅡ rs3741205 had no relationship with SGA;CT genotype of IGFⅠ rs35767 and TT homozygote of IGFⅡ rs3741205 increased the risk of LGA significantly(P = 0.045,P = 0.029). When mother’s educational background beyond the college,the IGFⅡ rs3741205 GT/TT genotype reduced the risk of LGA. Conclusion:IGFⅠ rs35767 is contribute to SGA. IGFⅠ rs35767,IGFⅡ rs3741205 are contribute to LGA.