Abstract: A leakage performance test rig for honeycomb seals was built. The leakage flow rates and the pressure distributions in the sealing chambers were measured for two groups of tooth rows under different clearances and pressure ratios, and the influence of tooth group number, clearance and pressure ratio on leakage and chamber pressure was analyzed through numerical calculations. Results show that as the pressure ratio increases, the leakage flow rates of honeycomb seals with different numbers of tooth rows and clearances increase sharply, and the variation rate of the leakage flow rate at a low pressure ratio (1.1~1.3) is higher than that at a high pressure ratio (1.9~2.1). When the pressure ratio is the same, the leakage flow rate increases with clearance increase. Increasing the number of tooth group can disperse the pressure drop, share the flow resistance, and reduce the kinetic energy of leakage flow and the leakage flow rate. At the same time, as the clearance decreases, the static pressure drop of gas flow in sealing chamber increases, and the sealing effect is enhanced. Especially under high pressure ratio (1.9~2.1) condition, the static pressure drop rate of the working fluid significantly accelerates after flowing through the third chamber.