Abstract: Myotonic dystrophy type 1 (DM1) is a multisystem trinucleotide repeat expansion disorder usually referred to the department of neurology with complaints of progressive muscle weakness and myotonia. This article reported a 33-year-old female patient with DM1 presenting with acute respiratory failure.Muscle biopsy in vastus lateralis showed significantly increased internal nuclei. Genetic test show CTG repeat expansions with the size of (847±76) in dystrophia myotonica protein kinase (DMPK) gene on chromosome 19. This case report broadens the clinician′s understanding of the atypical clinical manifestations of DM1, so as to avoid missed diagnosis and misdiagnosis.