We introduce the electrospinning method into fabricating oxygen-sensitive submicrometer scale optical fiber. Uniform tris (4,7-diphenyl-1,10- phenathroline) ruthenium(II) dichloride ([Ru(dpp)3] 2+Cl2)-doped fibers with a diameter of 900 nm are obtained by electrospinning the organic silicon sol solution derived from tetraethyl orthosilicate and n-Octyltriethoxysilane (C14H32O 3Si). The experimental results show that the single gel fiber exhibits excellent optical and sensing properties. A laser with a wavelength of 452nm can be efficiently launched into the fiber and guide along the fiber to excite the fluorescence. Then, we find that [Ru(dpp)3] 2+-gel fiber has favorable optical and sensing characteristics, and the Stern-Volmer plots are linear in the full concentration range of O 2 (0-100 vol: %). The ratio of I0/I100, where I0 and I100 respectively represent the fluorescence intensities of the fiber exposed to 100% N2 and 100% O2, as the sensitivity of the fiber is 3.5. Simultaneously, the fiber can make a quick response within 100 ms. This method provides an effective and convenient way to fabricate highly uniform nanoscale or microscale optical waveguides for photonic devices.