In terms of the coupled-mode theory, electro-optic modulation theory, conformal transforming method and imaging method, a transfer matrix technique is proposed for analyzing the high-frequency response characteristics of the polymer directional coupler electro-optic switches. Expressions of output power, rise time, fall time, switching time and cutoff switching frequency are deduced. The structures of waveguide and electrode are optimized for getting the minimum propagation loss, good matching impedance, low switching voltage and high cutoff switching frequency. Simulation results show that the switching voltage is about 1.457 V, coupling length is about 4.374 mm, switching time is about 32.8 ps, and cutoff switching frequency is about 114.7 GHz. Comparisons are performed among the results of this technique, those of the point-matching method, and the experimental results, which show that the proposed technique has high accuracy.