A 1×2 multimode interference Mach-Zehnder interferometer thermo-optical switch was designed by combining the advantages of organic polymer and inorganic SiO2 materials. The structural parameters were optimized and the device performances were simulated. Fabrication techniques, such as chemical vapor deposition and lithography, were adopted to fabricate the switch, and the waveguide appearance were characterized. Furthermore, in order to measure the performance of the device, a kind of measurement system for optical switch was developed using ARM7 processor and InGaAs photoelectric detector. The system is mainly composed of low-ripple linear power, photoelectric detector, preamplifier, main amplifier, signal regulator, AD converter, main controller, display module, etc. The system was calibrated with the help of a commerical optical power meter, and its zero drift is found to be smaller than 0.5 dBm. Applying different driving voltages on the electrode, the output optical power from one port of the switch was both measured by the self-developed optical power meter and the commerical power meter. the experimental results show that, the obtained two curves have the same variation trend, and when the driving voltage is 10 V, the two measured output powers both become the smallest. This shows that the measurement system has good performance and can meet the needs of the actual measurement. The system provides a solution for the performance measurement of optical switch due to its small size and high performance-cost ratio.