The structure of W band (2.73-4 mm) electro-optical phase modulator (EOM) is characterized by multi-parameters and complex design. Referring to the coplanar waveguide transmission line theory and EOM theory, and combining with the three-dimensional electromagnetic simulation high-frequency structure simulation software HFSS, we carry out the finite element analysis and calculation of the modulator. For key parameters in the geometry structure of the EOM, we carry out model simulation calculation in four dimensions, and establish the multi-dimensional mathematical model of the EOM. According to the simulation model, we obtain the variation rules of geometric parameters and main performance of the EOM, and establish the model structure of the EOM. Through structural optimization, we obtain the 100 GHz speed EOM model with matching speed, matching impedance, and small attenuation.