Abstract: Objective　To explore the role of night waking in the cognitive development of infants and young toddlers. Method A total of 116 infants aged 2 to 30 months were randomly selected in Yiwu, Zhejiang from December 2011 to February 2013. Social-demographic factors were investigated through questionnaire; sleep information were collected via the Brief Infant Sleep Questionnaire (BISQ); Cognitive development was assessed in all infants using Baley development scale. Results The mean age was 12.99 month-old. 50.86% (59/116) were males. Ocassional night waking was reported in 5.26%, one night waking in 29.82%, multiple night waking accounted in 64.91% of children under one year old. Ocassional night waking was reported in 32.20%, one night waking in 45.76%, multiple night waking in 22.03% of children over one year old. The frequency of night waking was significantly different between children under one year old and children over one year old (P<0.01). The average duration of waking was 0.49±0.31 h in children under one year old, and 0.31±0.48 h in children older than one year old, and the difference was significantly different (Z=4.35, P<0.001). In children over one year old, the more frequent night waking, the lowered MDI scores (F=3.98, P=0.024). The waking duration was negatively correlated with MDI scores in children over one year old (r=-0.26, P=0.035). Neither night waking duration nor night waking frequency had significant correlation with MDI scores in children under one year old. Multivariable linear regression confirmed that night waking was an independent influential factor of MDI and PDI scores in children over one year old. Conclusions Persistent night waking should warrant attention.