When the dry gas seal of spiral groove is in static state due to equipment troubleshooting or shutdown,its sealing performance has obvious difference and correlation compared with the seal in rotating state.The performance of the spiral groove dry gas seal was studied under static state.Based on the narrow groove theory of spiral grooves,the control equations for the gas film pressure between the sealing end faces of the spiral groove dry gas seal at rest were obtained and solved by an analytical method.The results show that as the boundary pressure or film thickness increases,the static leakage rate at rest is increased gradually,and when the static leakage rate reaches the maximum static leakage rate specified in the JB/T 11289-2012 Standard,the end faces are still in contact states.The opening force,the pressure at the root of the groove and the leakage rate in the static state are increased with the increasing of the groove depth,and then tend to be stable when the depth of the groove is greater than some value.As a whole,the opening force and leakage rate between the sealing end faces decrease with the increasing of the width ratio of the land to groove.However,when the width ratio of the land to groove is in the range from 0 to 10,the influence of the width ratio on the opening force and leakage rate is not obvious.