Objective To understand the sex ratio at birth and influencing factors of neonates born in hospital in Wuxi and explore the intervention measures, for laying the foundation of long-term research. Methods Using descriptive research method, the registration information of newborns were collected from all maternity hospital of Wuxi city from 2008 to 2012.The characteristic of sex ratio at birth was analyzed. Results The average sex ratio at birth was 112.42 from 2008 to 2012 in Wuxi city.The sex ratio at birth of the floating population was higher than that of native population.The average sex ratio at birth gradually increased with the age of mother (108.03~123.99) (trend test P<0.05), especially significantly increased among those more than 30 years (>117.87).Logistic regression model demonstrated that the floating population, maternal age ≥30 years old, parity ≥2 and uterine-incision delivery could be the factors of increased sex ratio(P<0.001). Conclusions The sex ratio was higher in Wuxi city.To improve the quality of the newborn population, measures should be taken to improve the monitoring quality.