Narcolepsy and multiple sclerosis are both related to autoimmune systerm, the clinical and diagnosis characteristics with narcolepsy and multiple sclerosis will be reported in this case.[Report of case] A 20-years old girl was reffered for evaluation for narcolepsy.2years ago, she was diagnosed with relapsing-remitting MS, she replased 3times, 2 months ago she showed excessive daytime sleep with Epworth sleep scale of 11 and sleep paralysis, she had no catalepsy and hallucinations, she could remit after using methylprednisolone, and she didn t use interferon beta, she has no narcolepsy family history, neurology examination was normal except for Eye vertical motion, both brisk patellar reflex, and both side Babinski sign positive, MRI of her showed lesions in pons and hypothalamus, polysomnography PSG did not show any evidence of sleep breath disorder and sleep periodic limb movement, subsequent multiple sleep latency testing showed reduced mean sleep latency and 2 of 5 sleep onset REM periods.Human leukocyte antigen subtypesDR2,DQB 1 of his cerebrospinal fluid was negative.[Conclusion] Narcolepsy may occur before and after multiple sclerosis ,patients with MS and excessive daytime sleep should be evaluated for narcolepsy, and narcolepsy patients should be assessed for multiple sclerosis.