Experimental models of straightthrough and stepped labyrinth seals were designed to study the sealing performance of different typical labyrinth seals.By experimental and numerical methods,the sealing performances of straightthrough and stepped labyrinth seals under different pressure ratio and sealing clearance were compared,the effects of relative axial location of stepped labyrinth seal on the leakage,as well as the pressure distribution of labyrinth seals were studied.The results show that,at the same sealing length,the leakage coefficient of stepped labyrinth seal is less than straight one by about 45%.The change of sealing clearance has smaller influence on the leakage of stepped labyrinth seal compared with the straight one,indicating that the stepped labyrinth seal has better sealing stability.The relative axial location has a little effect on the leakage under low pressure ratio.When the tooth tip is located at the middle of cover,the leakage of stepped labyrinth seal is the largest.The pressure distribution of stepped and straightthrough labyrinth seals is similar,which shows a linear decrease.The numerical results show a pressure valley at the tooth tip and a pressure peak at a position of the cavity,which is different from the experimental results.