A novel difference frequency generation (DFG) scheme for simultaneously achieving multi-wavelength mid-infrared (mid-IR) emissions based on a bulk PPLN crystal is proposed. For the combination of 1060 nm and 1550 nm wavelength band fundamental light sources, multiple pump quasi-phase-matching (QPM) peaks can be obtained by using the segmented temperature controlling techniques on a PPLN chip. Moreover, the multiple pump QPM peaks can be widely tuned by adjusting the segmented crystal temperatures and thus the tunability for the generated multiple mid-IR wavelengths is realized. Our simulated results show that when the PPLN crystal are evenly divided into two sections for temperature controlling, four pump QPM peaks are simultaneously reached, corresponding to the mid-IR idler QPM peaks at 2.95, 3.03, 3.75, 3.83 μm, as the signal wavelength setting at 1.58 μm and the segmented crystal temperatures setting at 20 ℃ and 60 ℃, respectively. When the segmented crystal temperatures are adjusted to 50 ℃ and 90 ℃, the idler QPM peak positions in the mid-IR DFG output spectrum are changed to 3.01, 3.11, 3.67, 3.77 μm. Such results may provide reference and guidance for design and development of widely tunable multi-wavelength DFG light sources.