Objective To investigate the level and the influencing factors of maternal attachment among mothers who have preterm infants admitted in NICU, and to provide reference for establishment of early mother-infant bonding. Methods A total of 285 mothers who had preterm infants admitted in NICU were recruited by convenience sampling. These mothers were asked to complete the Self-rating Anxiety Scale(SAS), the Edinburgh Postnatal Depression Scale（EPDS） and the Maternal Attachment Inventory(MAI). Multiple linear regression was used to analyze the influencing factors of maternal attachment. Results The 285 eligible participants scored 26 to 104 points in maternal attachment (median:71.00). Maternal attachment was influenced significantly by mother′s ages, family income, mother′s postpartum depression scores（P<0.05, P<0.01）. Conclusion NICU premature infants′ mothers have a moderate level of attachment. It′s recommended to ramp up education and guidance on maternal and infant attachment knowledge for mothers who are young, who are from well-off families, and who have depressive moods and to provide child-rearing support for mothers, so as to improve mother-infant bonding, and promote the mental health of children.