A method of electrospinning was established to fabricate organic silicon gel submicrometer optical fibers. First, Tetraethyl orthosiliate(TEOS) and n-Octyltriethoxysilane (Octyl-triEOS) were hydrolyzed and polymerized under an acidity condition. Simultaneously, the fluorescence indicator of tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride ［Ru(dpp)3Cl2］ was added into the solution to form a viscous sol solution. Then, the electrospun fiber with a diameter of 900 nm was obtained by electrospinning the sol solution under a high voltage of 10 kV in the electrostatic field. A tapered multimode optical fiber was coupled with the electrospun optical waveguide fiber through an evanescent field and the sensing characteristic of the electrospun fiber was tested at the same time. Experimental results indicate that the electrospun (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride doped silicon gel fiber has a smooth surface and a uniform diameter. The light can be highly coupled into the electrospun fiber through the evanescent field and can excite the indicator molecules in the fiber to emit a 595 nm fluorescence. This fiber is sensitive to the oxygen gas in the range of 0~100 %(volume ratio),and the quenching degree of I0/I is linear to the concentration of oxygen in the range. The response time is below 100 ms.