The continuity equation and momentum equation of the flow through a sectorial element in labyrinth seal is linearized according to the presumption of the small disturbance and solved with the aid of matrix method.Then the distribution of the pressure on the cylindrical surface of rotor is obtained.Finally

the flow induced force on rotor is evaluated by means of integration.Numerical example indicates that as the number of seal chamber increases

the flow induced force increases while the leakage flow rate decreases;when the seal clearance increases

the flow induced force decreases while the leakage flow rate increases;but both the flow induced force and leakage flow rate decrease when the exit pressure increases.