An organic/inorganic hybrid 2×2directional coupler Mach-Zehnder int erferometer (DC-MZI) thermo-optic (TO) switch is designed and fabricated by using the negative photo resist SU-8,polymer PMMA and silica as core,upper cladding and lower cladding,respectively.The structural parameters are optimized for assuring fundamental mode propagation,decreasing radiation loss and leakage los s,shortening response time and minimizing power consumption.Fabrication techniques,including spin-coating,w et-etching,etc,are adopted to develop the device sample.Under 1550nm,the driving power at cross state and t hat at bar state are measured to be 0and 7.8mW,respectively,which indicates a switching power of 7.8 mW.The cro sstalks between the two ports under cross state and bar state are －9dB and －12.8dB,respectively.Under the function of square-wave switching signal,the rise time and fall time of the cross-port are 138μs and 136μs, respectively,and those of the bar-port are 63μs and 140μs,respectively.Compared with the thermo-optic switches with Si/SiO_2structure and full polymer structure,the proposed hybrid device possesses lower power consumption and faste r response simultaneously,owning to the advantages including larger TO coefficient for polymer core material,thin ner upper/under claddings and larger thermal conductivity of silica relative to pol ymer.