Scintillating silica optical fibers are fabricated by using Sol- Gel method. Based on the fabricated scintillating fibers, a Gamma radiation fiber sensor system is set up. Through doping different concentrations of cerium (Ce) element in Sol-Gel material, two scintillating fibers are fabricated with the Ce and Si mole fraction of 0.14% and 0.22%. By using a 137Cs Gamma radiation source, the dependences of the sensing properties on the fiber coating, Ce-doped concentration and fiber length are investigated and analyzed.