The characterization and design of LiNbOa optical modulators of novel electrode structures are discussed by using the finite-clement method (FEM) and the incremental inductance formula. Loss coefficients are verified in this paper. The calculation results show that the structures can realize microwave-optical velocity match easily and reduce microwave electrode losses drastically, so the modulators employing such structures are candidate devices for future ultra- high- speed optical fiber transmission systems. The electrode structures are optimized by using the ratio of the 3 dB optical bandwidth to driving power as a standard. The results of optimization show that the properties of the modulators can be improved by increasing the electrode gaps. As an example, an electro-optic modulator, whose bandwidth is 100 GHz, half wave voltage is 6 and driving power is 0.48 W, is designed.