Objective To study the patterns and diameters of posterior circulation in patients of sudden sensorinerual hearing loss(SSHL), and to provide anatomical evidence for the vascular etiology of SSHL.   Methods The craniocerebral images of 3.0T time of fly magnetic resonance angiography (3.0T TOF MRA) of 180 patients diagnosed with sudden deafness in one ear and 102 control patients were retrospectively analyzed. Clinical data including age and gender distribution, level of low-density lipoprotein(LDL), total cholesterol(TC), triglycerides(TG), fibrinogen and velocity of blood in basilar artery were compared. Subsequently, diameter and patterns of basilar artery, diameter and dominance of vertebral arteries, visible rate and diameters of anterior inferior cerebellar arteries (AICA), and diameter and patterns of P1 segment of posterior cerebral arteries(PCA) and posterior communication arteries（PCoA）were compared between the two groups. Statistical method  were used for analysis.   Results Clinical data showed that the proportion of increase (34.44%)and significantly increase(11.22%) of LDL level in peripheral blood of SSHL group were higher than that of the control group (15.69% and 4.9%), and the proportion of increase (24.44%)and significantly increase(11.11%) of TC level in peripheral blood of SSHL group were higher than that of the control group (19.6% and 2.94%). MRA imaging result  showed that the mean diameter of basilar artery in SSHL group(3.32±0.75 mm) was narrower than that in the control group (3.50±0.54 mm)(P<0.05);The imaging rate of only left AICA in SSHL group(10%) was lower than that in the control group (24.51%)(P<0.05);The invisible rate of bilateral AICA in SSHL group (38.89%) was higher than that in the control group (26.47%)( P<0.05);The overall distribution of AICA imaging status in two group was statistically significant(P<0.01). The mean diameter of imaged left side AICA in SSHL group (1.04±0.24) mm was narrower than that in the control group (1.16±03.28) mm (P<0.05). The mean diameter of left side P1 segment of PCA in SSHL group(1.27±0.54) mm was narrower than that in the control group (1.42±0.52)mm (P<0.05);The mean diameter of left right side P1 segment of PCA in SSHL group(1.25±0.58)mm was narrower than that in the control group (1.41±0.51) mm (P<0.05). The proportion of fetal posterior cerebral artery (fPCA) only on the left side of SSHL group(3.33%) was lower than that of the control group(9.8%)(P<0.05);The proportion of bilateral fPCA of SSHL group(13.89%) was higher than that of the control group(4.9%)(P<0.05);The difference in the overall distribution of the presence of fPCA between the two groups was statistically significant(P<0.01).   Conclusion There is stenosis of the basilar and branch arteries, due to a high level of low-density lipoprotein and cholesterol in patients of SSHL.