Vascular pulsatile tinnitus is a common and serious symptom, but no clear biomechanism. According to clinical radiographic reports, coloboma of cortical plate attaching sigmoid sinus occurs widely among patients, and most of them can be cured through cortical plate reconstruction surgery. Therefore cortical plate coloboma is a high-possibility etiology causing vascular pulsatile tinnitus. To study the mechanical relationship between cortical plate coloboma and vascular pulsatile tinnitus, finite element models of sigmoid sinus flow field and cortical plate were developed based on CT images. The generation and propagation of tinnitus noise were simulated separately. The model with and without cortical plate were analyzed to make comparison. The evaluation result provided a mechanical conclusion that coloboma of cortical plate attaching sigmoid sinus would remarkably amplify the noise generated in sigmoid sinus, therefore directly leading to audible perception. The conclusion also positively supported the cortical plate reconstruction surgery to cure vascular pulsatile tinnitus.