In this work, we numerically demonstrate an all-optical tunable Fano resonance in a fishnet metamaterial(MM) based on a metal/phase-change material(PCM)/metal multilayer. We show that the displacement of the elliptical nanoholes from their centers can split the single Fano resonance (FR) into a double FR, exhibiting higher quality factors. The tri-layer fishnet MMs with broken symmetry accomplishes a wide tuning range in the mid-infrared(M-IR) regime by switching between the amorphous and crystalline states of the PCM (Ge 2 Sb 2 Te 5). A photothermal model is used to study the temporal variation of the temperature of the Ge 2 Sb 2 Te 5 film to show the potential for switching the phase of Ge 2 Sb 2 Te 5 by optical heating. Generation of the tunable double FR in this asymmetric structure presents clear advantages as it possesses a fast tuning time of 0.36μns, a low pump light intensity of 9.6μ4W/μm 2, and a large tunable wavelength range between 2124μnm and 3028μnm. The optically fast tuning of double FRs using phase change metamaterials(PCMMs) may have potential applications in active multiple-wavelength nanodevices in the M-IR region.