ZGP crystals possess large nonlinear coefficients (d36=75pm/V), wide infrared transparency range(0.75-12μm), high thermal conductivity(0.35W/(cm·K)), high laser damage threshold (2-5J/cm2)and well machining property, ZnGeP2 crystal was called the king of infrared nonlinear optical crystals and is still the best frequency conversion material for high power, tunable infrared laser generation. We can offer high optical quality and large diameter ZGP crystals with extremely low absorption coefficient α < 0.02 cm-1(at pump wavelengths 2.0-2.1 µm), which can be used to generate mid-infrared tunable laser with high efficiency through OPO or OPA processes.