Based on the formation of a red [Cd-diphenylcarbazide] complex, a simple and visible method for Cd²⁺ colorimetric detection was developed by doping SiO₂ nanoparticles and diphenylcarbazide in polymethylmethacrylate electrospun fibers. Benefiting from the large surface area due to the addition of SiO₂ nanoparticles, the color of the fibrous film changed clearly even in the presence of extremely low concentrations of Cd²⁺. The detection limit was found to be 1 × 10⁻⁸ M. Investigation of the selectivity of the fibrous film on the detection of various metal ions showed that only Cd²⁺ could induce a yellow-to-red color change. The results demonstrated that SiO₂ and diphenylcarbazide doped polymethylmethacrylate fibrous films could act as highly selective strips for the detection of Cd²⁺ with little interference from other metal ions.