Premature infants in the NICU are vulnerable to harmful stimuli such as sound and light, which often disrupt and interrupt their sleep, as their organs are not yet mature and their sleep cycles are not yet established. The disruption of sleep has a negative effect on the nerve and growth and development. This review introduces the sleep cycle of premature infants, assessment tools and promotion strategies，so as to improve the cognition of medical staff on sleep protection of preterm infants and provide references for clinical practice in promoting sleep development of premature infants