Abstract: Objective: To study the relationship between sigmoid sinus and its adjacent structure in order to provide an anatomic basis for otochirurgia.Methods: The distance between sigmoid sinus and its adjacent structure was measured respectively based on the simulation of transmastoid approach.Results: The distance between the precingular plale of sigmoid sinus and the external auditory superameateal spine was(13.28±1.87) mm.The distance between sigmoid sinus and the surface of mastoid was(5.16±0.73) mm.The distance between sigmoid sinus and external auditory superameatal spine was(17.85±1.62) mm.The distance between sigmoid sinus inferior genu and external auditory superameatal spine was(19.68±2.11) mm.The distance between sigmoid sinus and the short process of incus was(17.37±1.54) mm.The distance between sigmoid sinus and the horizontal semicircular canal was(14.61±1.37) mm.Conclusions: It has guidance significance to measure the distance between sigmoid and the surface of mastoid,external auditory superameatal spine,and the other adjacent structure for the transmastoid approach.