A strip titanium dioxide (TiO₂) waveguide is designed for highly coherent mid-infrared (MIR) supercontinuum (SC) generation. For the designed TiO₂ waveguide, three zero-dispersion wavelengths (ZDWs) are obtained through adjusting the waveguide structure parameters. The three ZDWs are located at 1.53, 3.96, and 5.43 μm, respectively. The nonlinearity coefficient γ is calculated as 1.12 W ^{− 1} m ^{− 1} at wavelength 3.1 μm. By optimizing the pump pulse parameters, the highly coherent MIR SCs are generated when the hyperbolic secant pump pulse with a duration of 80 fs, peak power of 1 kW, and wavelength of 3.1 μm is launched into the TiO₂ waveguide and propagated 4.2-mm in length. The obtained SC covers a wavelength range from 1.71 to 9.90 μm (more than 2.5 octaves). Our research results can find important applications in MIR photonics and spectroscopy, biophotonics, optical precision measurement, etc.