Dry gas seal is an important sealing form of high-speed shaft,and changing its contact gap rheological characteristics through the spiral groove seal design is an important means to improve its friction wear.In traditional research,the uneven distribution of the gas film caused by the gap in the grooving area of the sealing contact surface is easily ignored,which causes errors in the analysis of rheological properties and affects the study of tribological characteristics.Based on the flat plate model,considering the unevenness of gas film distribution,an average gap model was proposed to describe the gas rheological characteristics of the dry gas seal grooving area,and to realize the calculation of friction torque at the contact interface,so that the numerical calculation error could be reduced.Through the numerical simulation of the gas film rheological characteristics,the relationship between the viscosity of the key parameters and the rheological characteristics was determined,and the influence of working parameters such as speed and spiral groove structural parameters on the friction characteristics of the gas film was obtained.