Sleep takes an important role in maintaining typical development, neural plasticity, and language development. Not only poorer performance in memory and cognitive functions, but also obvious delayed language development are seen in children and adolescents with sleep problem. Previous research found that sleep duration affects children and adolescents' ability in comprehensive vocabulary, expressive vocabulary, and vocabulary retention. Children and adolescents with poor sleep quality usually show language developmental delay, however, there is no integrated evaluation tool for sleep and language, and a consistent conclusion is therefore not reached. Daytime naps are beneficial to consolidate vocabulary learning in infants, and it’s also relevant to vocabulary retention and generalization in children and adolescents. Children with sleep related breathing disorders show lower ability in receptive language comprehension and lower lexical level, and with the increase of their age, the severity of their language disorder becomes higher. Besides, sleep can promote language learning in children with neuro-developmental disorder.The neuro-physiological mechanism underlying sleep and language remains unknown, and one of the possible explanations is that sleep problem harms the information processing in frontal lobe and hippocampus, and interferes with neural plasticity. The injury includes memory, attention, executive function, auditory processing, and so on, and finally language development is damaged. Further research is necessary to clarify the relation and mechanism between these two elements, this will be helpful in finding out an effective way to promote language function in children with language retardation and/or combined with neuro-developmental disorder.