An optical fluoride probe was fabricated based on Microstructured Polymer Optical Fibers (MPOFs) modified by morin-Al complex doped silica gel films. The structure of this probe was based on microstructured polymer optical fibers with microholes and these microholes could be used as the substrate of sensing materials and minor reaction pools. The deposition of sensing layer was realized by a sol-gel process. When the sol doped with morin-Al was inhaled into the optical fiber, the sensing layer was formed on the inner wall. Furthermore,the trace liquid could be hold in the MPOF, and the process of sensing were carried out in the microholes of MPOF. The sensing process was undertaken based on fluorescence process, and the sensing probe shows different fluorescence intensities to different fluoride ion concentrations in the aqueous solution,for the fluoride ion has a stronger queeching effect to the morin-Al in gel matrix. Experimental results show that the range of response is 5-50 mmol/L under the condition of pH in 4.6.