To eliminate the negative effect of the fabrication error on the performance for the directional coupler electro-optic switch with single-section electrode,the structure is designed,the parameters are optimized,and the characteristics are analyzed for a polymer directional coupler electro-optic switch with two-section reversed electrodes by using the coupled mode theory,electro-optic modulation theory,conformal transforming method and image method.Simulation shows that the designed device exhibits excellent switching functions.Under the operation wavelength of 1 550 nm,the coupling region length is 4 753.5 μm,the cross-state and bar-state voltages are about 1.22 V and 2.65 V,and the insertion loss and crosstalk are less than 2.21 dB and -30 dB,respectively.By slightly adjusting the state voltages,the blight of the fabrication errors on the switching characteristics can be easily eliminated.The calculation results of the presented technique are in good agreement with those of the beam propagation method (BPM).