Objectives: To explore the principle and efficacy of surgical modification of extravascular conditions in the sigmoid sinus for the treatment of pulsatile tinnitus through the combination of physical modeling, biophysical field threshold theory acoustic analysis and Transmastoid Sigmoid Sinus Wall Reconstruction (TSSWR). Methods: Mimics, Geomagic Studio, and Creo Parametric software was employed to simulate the modeling of sigmoid sinus and bony boundary conditions. To analyze the biophysical field associated with the sigmoid sinus by physical acoustic analysis. Search for the points responsible for the location of the sound source in the intraoperative exploration according to preoperative CT imaging, combined with postoperative effect analysis, used to make it clear. Results: Five 3D finite element models with different bony boundary conditions of the sigmoid were established. Theoretical analysis suggests that the sound source originates from the vibration of blood vessels in the bone defect of the sigmoid sinus wall. The sound is transmitted by compressive bone conduction through a central-type bone septum in contact with the exposed vessel wall. The loudness of the sound is related to the peak pressure of the sigmoid sinus wall and the transmission efficiency of the bony septum. Nine patients underwent TSSWR treatment, including two patients with sigmoid sinus diverticulum. They were followed up in 5 to 50 months without recurrence of tinnitus. Sound sources were found at the high-risk site of tinnitus, the junction of transverse-sigmoid sinus in 8 cases, it was found at the low-risk site of the descending part of the sigmoid sinus only in 1 case. Conclusions: The bone wall defect and the corresponding central-type bony septum may be the necessary condition for PT secondary to the SSWAs. It can be accurately positioned and dealt with safely and easily to achieve a better therapeutic effect.