Abstract: With regard to the problems of a dry gas seal (DGS) under high speed conditions, e.g. large leakage rate and insufficient gas film stiffness, a new type of Pyramid-like groove dry gas seal (PL-DGS) was introduced on the basis of spiral groove DGS structure and the superimposed combined conception. Geometric and mathematical model of PL-DGS were set up according to the theory of gas lubrication. A two-dimensional steady Reynolds equation was solved to obtain pressure distribution at end face by using the finite difference method (FDM). Taking the maximal gas film stiffness as optimization objectives, comparative analysis of sealing performance between different structural types of optimal superimposed combined grooves and common spiral groove dry gas seal was conducted. Numerical simulations were carried out to analyze the influence of groove depth and groove width in circumferential, radial direction on sealing performance, and the optimization of the main geometric parameters of PL-DGS was also demonstrated. The results show that this new type of DGS could keep the leakage rate almost unchanged and significantly improve gas film stiffness. Comprehensive sealing performance was much better compared to common spiral groove dry gas seal at high speed and low pressure. Moreover, the higher the speed, the lower the pressure. Hence the performance advantages were more obvious.