Abstract Universal structure and thorough analysis were proposed for a kind of polymer optical switch using N-th order microring resonator side-coupled Mach–Zehnder interferometer (MRR-SC-MZI). Formulation and expression of output power, insertion loss and crosstalk were derived, and detailed design and optimization were carried out. Analytical results indicate that all devices for N≥1 can perform normal switching function, and 8≥N≥2 is preferred for dropping the driving voltage below 5V. For the seven MRR-SC-MZI EO switches (N=2–8) whose cross-state voltages are within 0–2.32V, their bar-state voltages are within 0.96–4.83V and their insertion losses are within 0.35–0.85dB at bar state, whereas those within 0.14–1.70dB at cross state; their crosstalk are within −20.79 to −31.11dB at bar state, whereas those are within −13.86 to −20.36dB at cross state; their 3-dB electrical bandwidths are within 18.5–28.0GHz, and 3-dB optical bandwidths for the two output ports are within 18.1–40.0GHz and 32.0~55GHz, respectively. Comparison indicates that the driving voltages of the proposed MRR-SC-MZI switching devices are 10–250 times smaller than those of the traditional MZI EO switches with the same EO region length, device length and structural parameters. Therefore, due to small footprint size and low driving voltage, this switching configuration can be densely integrated onto optoelectronic chips.