According to the structure characteristics of single row spiral groove in cylindrical spiral groove dry gas seal,the mathematical analysis model of spiral groove floating ring gas film seal was established.Based on the central difference method and NewtonRaphson iteration method,the pressurecontrolled Reynolds equation and the film thickness equation were solved.The distribution of pressure and gas film thickness and the leakage of the single row spiral groove film under different operating parameters were obtained.The influence of operating parameters on the steadystate performance of the spiral groove was discussed.The results show that the leakage is increased with the increase of eccentricity and pressure.When the eccentricity is fixed,the increase of rotating speed leads to the decrease of leakage.When the rotating speed is fixed,the increase of pressure leads to the sharp increase of leakage,which is almost linear distribution.The experimental results are consistent with the theoretical analysis results,which verifies the correctness of the theoretical model and calculation method