On the basis of permanent magnet linear synchronous motor (PMLSM) feeding system mechanical model, effects of normal force of moving parts in different stroke to deformation of a gantry type beam were analyzed by finite element method. A curve corresponding to y irectional deformation of the beam was achieved and the deformation of the beam was measured. The normal force of PMLSM was achieved by finite element simulation and relevant experiments. Deformation of the tool point was analyzed by finite element method and compared with the experimental results. The simulation results were verified to be reliable. 