Numerical method was used for simulating the flow fields and studying the sealing performance and dynamic characteristics of straightthrough,stepped and staggered labyrinth seals.The effects of rotor speed and pressure on leakage and dynamic characteristics were investigated.The results indicate that staggered labyrinth seal has the best sealing performance among three kinds of seals,while the straightthrough type has the worst sealing performance.Straightthrough labyrinth seal has better dynamic characteristics at high speed,while the staggered type has better dynamic characteristics at low speed,but its dynamic performance falls sharply with the increasing of rotor speed.At low rotor speed or high pressure difference,staggered labyrinth seal has better sealing performance and dynamic characteristics,while the stepped type has the worst sealing performance and dynamic characteristics.At high speed,straightthrough labyrinth seal has better dynamic characteristics,while the staggered type has the worst dynamic characteristics.