Abstract: The stiffness and dynamic characteristics of grinding wheel dresser spindles have a significant influence on dressing accuracy and the machining precision of guideway grinders. In this paper, the vertical and horizontal grinding dresser spindles of a guideway grinder are taken as research objects. Static analysis is performed to obtain the maximum deformations of the two spindles under corresponding working conditions, and their equivalent static stiffness values are calculated. Then, modal analysis is carried out to calculate their first to sixth natural frequencies and corresponding critical speeds. Finally, harmonic response analysis is conducted to evaluate the possibility of resonance under radial excitation forces. The results show that the equivalent static stiffness of both spindles meets the service requirements. Modal analysis indicates that the critical speeds of both spindles are far higher than the rated speed. Harmonic response analysis demonstrates that the resonant frequencies of both spindles are much higher than the actual operating frequencies, so there is no risk of resonance. Both spindles possess good static and dynamic characteristics, and the findings can provide a theoretical reference for the design and selection of dresser spindles.