A new type of labyrinth seal with semi-Y of rotor teeth (SYLS) is proposed in this paper. The rationality and accuracy of the numerical model are validated by the experimental results, and the static characteristics are investigated. Furthermore, the effects of pressure drop, rotation speed, tilt angle, and tip clearance on the dynamic coefficients and stability are also studied in detail. The results imply that the novel SYLS structure generally has better leakage and stability performance compared with the traditional labyrinth seal. The maximum error applied in the numerical simulation is only 2.81%, and the worst leakage occurs when the tilt angle is 70° for the SYLS structure due to the smaller vortex dissipation. Moreover, the novel SYLS structure shows the best stability when the tilt angle is 45°. The novel SYLS structure and corresponding results can provide a reference for the research and design for labyrinth seal and the application of centrifugal pump.