By using microstructured chalcogenide fibers, split-step Fourier algorithm and nonlinear Schrdinger equation (NLSE), effects of centre frequency and pulse width of seed pulse on mid-infrared supercontinuum (SC) generation are studied. The microstructured chalcogenide fibers used here have high nonlinear effect and two zero dispersion wavelengths (ZDW). The second ZDW is in mid-infrared, which is helpful to mid-infrared SC generation. There are marked effects of centre frequency and pulse width of seed pulse on SC generation. In numerical stimulation, seed pulses have different frequencies and durations. Mid-infrared SC generation whose input wavelength is near ZDWs is wider than those far from ZDWs. When keeping peak power invariable, frequency spectrum broadened by pulse width is steady, but the shorter pulse can generate smoother mid-infrared SC.