We present a complete model and design approach for high speed electro-optic (EO) polymer modulators. A general numerical model for arbitrary travelling-wave EO modulators is built, and the dispersion characteristic of each polymer layer in the device stack is carefully considered and integrated into the model. A velocity compensation layer is added to allow more room for increasing the waveguide core index to optimize half-wave voltage of the device. Microstrip mode analysis is also included to estimate the influence of different polymer stack to the E filed distribution inside the waveguide core. The device has been successfully designed and achieves more than 45 GHz EO bandwidth with a half-wave voltage of 3.2 V. A 100 Gbps EO modulator is under development.