Maladaptive daydreaming（ MD）， also called the excessive daydreaming or compulsive fantasy， is a fantasy activity described as a behavioral addiction for vivid fanciful imagery， which interferes human interaction and/or interferes with academic， interpersonal， or vocational functioning. Based on previous research， this paper synthesizes the current status of research on maladaptive daydreaming， including the concept， measurement， structured clinical interview， as well as the comorbidity on attention deficit hyperactivity disorder（ ADHD）， obsessive-compulsive disorder（ OCD） and other mental disorders in Diagnostic and Statistical Manual of Mental Disorders（ DSM-5）. This paper also introduces the antecedents， features， maintenance factors and results of MD. Future research should expand the sample to explore MD in the Chinese context， and further study the antecedents and comorbidity of MD， so as to develop treatment models and early intervention methods.