The infrared nonlinear crystal CdSe has attracted more attention recently because of its special optical properties, including low optical losses and long wave high tunability efficiency at λ>8μm with non-multi-phonon absorption, making it one of the leading candidates for use as nonlinear optics devices for frequency conversion, especially 8～12μm. CdSe polymaterial was gained by element reaction directly at high temperature, then single crystal was grown with temperature gradient solution zoning (TGSZ) method, and crystal with 19 mm in diameter and 70 mm in length was obtained. The polymaterials were studied by X-ray power diffraction (XRD) and ICP-MS methods to check the purity, and the single crystal slices were investigated by infrared microscope and spectrophotometer,which showed that the absorption coefficient α is about 0.08 cm-1 among 3～20μm, so it can be used as elements in some laser experiments.