Abstract: We present the case of an 18-year-old male patient who had narcolepsy type 1 and comorbid schizophrenia. The patient's first symptom was mainly excessive daytime sleepiness, which was followed by psychotic symptoms, including hallucinations, delusions, and abnormal speech and behaviors. After admission to the hospital, the patient underwent a number of ancillary tests. Multiple sleep latency test (MSLT) showed that the mean sleep latency was 2 min and the hypocretin-1 was found to be 90.56 pg/mL. The patient was diagnosed with: 1) schizophrenia; 2) narcolepsy. After receiving antipsychotic drugs and behavioral therapy, the patient's hallucinations and abnormal speech and behaviors disappeared, and delusions and excessive daytime sleepiness decreased significantly. The symptoms and manifestations of narcolepsy type 1 overlaps with those of schizophrenia, which may lead to misdiagnosis and underdiagnosis in clinical practice. The case is presented with a view to providing a reference for the clinical diagnosis and treatment of narcolepsy type 1 with comorbid schizophrenia.