Abstract: The leakage characteristics of the real-size labyrinth were investigated experimentally.The influences of geometric parameter and rotational speed were analyzed.The results show that:(1) in the experimental range,leakage coefficient increases with increasing Reynolds number.(2) Leakage coefficient decreases with increasing labyrinth number.(3) Leakage coefficient decreases with increasing clearance under the same Reynolds number.(4) Rotational speed has little effect on the leakage coefficient under small clearance(s=0.4,0.5 mm);when clearance is 0.6mm,rotational speed has definite effect on the leakage coefficient,i.e.2000r/min.