Objective To explore the relationships between the sleep/wake-up patterns and temperament in preterm infants.Methods The developmental characteristics of sleep/wake-up patterns and temperament in preterm infants aged 4 months at corrected gestational age in their own home environments were described.The 23 relatively low-risk preterm infants were enrolled in this study.The sleep/wake-up data was collected with actigraphy.The temperament was assessed by Chinese Infant Temperament Questionnaire.Results Among the 23 infants,there were 13 coordinated difficult(D) type and 10 coordinated easy(E) type.The number of night wake-up in the coordinated D-type preterm infants[(2.78 ±0.01) times] were significantly more than that of coordinated E-type ones[(2.60 ± 0.03) times] (t =3.285,P =0.001).The longest continuous sleep time of coordinated D-type preterm infants [(4.20 ± 1.21) h] was significantly less than that of coordinated E-type ones[(4.41 ± 1.14) h] (t =3.374,P =0.001).There were no significant differences in daytime sleep duration,the number of naps,bedtime,sleep latency,nighttime sleep duration,the 24 hour sleep duration and morning awaking time between the two groups (all P ＞ 0.05).After the sex factor was controlled,there was a positive correlation between emotional nature and sleep latency at night (r =0.599,P =0.032).There was also positive correlation between persistence and the number of naps in daytime (r =0.439,P =0.035).Conclusions Preterm infants with different temperament types have different number of night wake-ups and the longest continuous sleep time.The emotional nature and persistence are associated with sleep latency at night and number of naps in daytime respectively.The parents of preterm infants should change their child rearing behaviors to improve sleep quality of the preterm infants.