To analyse the 3D-Flair MRI manifestations of the inner ear, vestibular function status, and their correlation with hearing treatment outcomes in patients with severe sudden sensorineural hearing loss (SSNHL), and to explore potential prognostic indicators for sudden deafness. The clinical data of adult patients with unilateral profound sudden sensorineural hearing loss were retrospectively analyzed in Otorhinolaryngology Department of Shandong Provincial ENT Hospital from March 2018 to August 2020. Patients were categorized based on the results of their inner ear 3D-Flair MRI into two groups: the normal MRI group and the abnormal MRI group. The abnormal group was further divided into three subgroups: those with non-absorbed high signal in the inner ear, those with absorbed high signal, and those with destruction of the blood-labyrinth barrier. SPSS 26.0 statistical software was applied to analyze the differences in hearing efficacy, caloric tests, vestibular evoked myogenic potentials (VEMP), video head impulse tests (vHIT), and the incidence of dizziness/vertigo among various patient groups. A total of 191 patients with complete data were collected (97 males and 94 females, aged from 13 to 69 years old). There were 50 cases in the normal inner ear 3D-Flair MRI group. A total of 141 cases were found in the group with abnormal 3D-Flair MRI, including 50 cases of high signal unabsorbed, 71 cases of absorption high signal and 20 cases of blood labyrinth barrier destruction. There were no significant differences in age, sex, lateral ratio of hearing loss and course of disease among four groups (all >0.05).The significant efficiencies of hearing recovery, in the group with normal 3D-FLAIR MRI were better than those in the abnormal group (<0.05) after treatment. Among the four groups, there were significant differences in the apparent efficiency and total effective rate between the normal group and the inner ear high signal absorption group (²=4.007, =0.045; ²=6.925, =0.009). The abnormal rates of bithermal caloric test, vHIT results and dizziness/vertigo symptoms in the abnormal group were higher than those in the normal group (<0.05). There were significant differences in oVEMP abnormality rate, vHIT abnormality rate and incidence of dizziness/vertigo among the three groups with 3D-FLAIR MRI abnormality (<0.05). There were significant differences in caloric test, oVEMP, vHIT abnormality rate and incidence of dizziness/vertigo among the four groups (<0.05). The positive rates of caloric test, cVEMP test and vHIT test in patients with dizziness/vertigo were higher than those in patients without dizziness/vertigo (<0.05). The abnormal rates of posterior semicircular canal and horizontal semicircular canal in patients with dizziness/vertigo were significantly increased (<0.05) than patients without dizziness/vertigo. The recovery rate, effective rate and total effective rate of patients without dizziness/vertigo were significantly better than those with dizziness/vertigo (<0.05). The 3D-Flair MRI of the inner ear and vestibular function tests have reference value for the prognosis assessment of patients with severe sudden sensorineural hearing loss. Abnormal 3D-FLAIR MRI of the inner ear, especially absorption high signal, is associated with high incidence of vestibular dysfunction and dizziness/vertigo, with poor prognosis. Patients with severe sudden sensorineural hearing loss who have symptoms of dizziness/vertigo are more likely to exhibit abnormal results in vestibular function tests, with a higher susceptibility to involvement of the posterior and horizontal semicircular canals.