A design of directional coupler based polymeric electro-optical switch is presented, focusing on the reduction of both wavelength dependence and the sensitivity of optical characteristics to coupling length. A optimized configuration of the switch was found with a <0.3 dB insertion loss variation for the coupling length to change from 3800 to 4300 μm, making it feasible to form the polymer structure on silicon substrate by rubber molding process or other rapid printing techniques. The characteristics of the optical switch were analyzed by BPM simulations and an insertion loss as low as 0.4~0.6 dB was obtained, along with a crosstalk of-32 dB and a PDL of 0.08 dB. The driving voltage was found to be 42 V when r_~33 =14 pm/V.