Two parallel three-dimensional single-mode channel waveguides spacing of 75 μm were prepared on glass substrate by standard photolithography combined with K+-Na+ ion exchange. By use of sputtering technique,a tapered film of TiO2 with thickness < 30 nm was then deposited on the middle region of one channel to form a composite optical waveguide. On the basis of the tapered velocity coupling theory,the fundamental transverse electric mode can propagate through the TiO2-covered region with a low attenuation,leading to a significantly enhanced evanescent field in this region. Therefore,the composite waveguide can serve as the sensing arm and the naked channel waveguide as the reference. With the prism-coupling method the linearly polarized He-Ne laser light was simulatenously launched into the two channels,and the divergent light emitted from the two channels are superposed to yield the Young′s interference pattern. The interferometer signal was interrogated using a slit-photodetector system. Such a novel integrated optical Young interferometer is applicable to the ultra-trace detection of chemical and biological measurands.