A design method of micro-ring resonator based optical switches capable of simultaneously providing the transmission of transverse electric and transverse magnetic modes was presented, which can be applied to the buildup of polarization-independent switch chips operating in a given wavelength plane. In order to realize polarization-independent transmission, transverse electric mode and transverse magnetic mode should both work at the same resonant peak and the group refractive index of these two modes are equal to each other in this resonant wavelength. The silicon-on-insulator based micro-ring parameters were optimized with MODE Solutions, the chip simulation model was then set up by Interconnect to investigate transmission and transfer characteristics of the optical switch chip. By optimum design, the resulting micro-ring resonator based optical switching chip had a very low polarization dependent loss of 0.13 dB, while the transmission delay was 42.5 ps. Simulation shows that the length variation of the micro-ring resonator should be smaller than about 10nm for the polarization dependent loss of 1 dB, in which the thermo-optic effect can be used to compensate for the fabrication error with the perimeter change of 2.2 nm/K.