Sudden sensorineural hearing loss (SSHL) is a common disease in otolaryngology, with sudden onset, unknown cause, unilateral presentation being more common, and bilateral sudden sensorineural hearing loss (BSSHL) is rarer. BSSHL is further divided into simultaneous bilateral sudden sensorineural hearing loss(si-BSSHL) and sequential bilateral sudden sensorineural hearing loss(se-BSSHL) based on the interval between the onset of symptoms in both ears. BSSHL often results in severe or profound hearing loss, with severe clinical symptoms and high disability rate, poor prognosis, and unclear cause and pathogenesis. Current research mainly focuses on factors such as inner ear microcirculation, autoimmune response, and viral infection. This review summarizes the existing research findings and provides a detailed discussion of the possible causes and mechanisms of BSSHL, with the aim of providing evidence for the diagnosis and treatment of BSSHL and prevention.