In recent years, transition metal telluride (TMTs) has attracted extensive attention and research in the scientific field due to its unique crystal structure and excellent physical and chemical properties. In this paper, CoTe₂ quantum dots (QDs) was prepared by ultrasonic method, the morphology and structure of the prepared CoTe₂ QDs were characterized by TEM, AFM, EDS, XPS, XRD and FTIR. The optical properties of the prepared CoTe₂ QDs were investigated by Spectrophotometer (UV-Vis), Photoluminescence (PL) and Photoluminescence Excitation (PLE). CoTe₂ QDs shows good dispersion, uniform particle size and spherical morphology. The average diameter and height of the grains are about 3.1 nm and 2.9 nm respectively. CoTe₂ QDs shows the obvious absorption in the infrared band, and the absorption value decreases with the increase of dilution concentration. When the wavelength of excitation light and emission light increases in turn, the PL and PLE peaks have a red shift, and they have an obvious Stokes shift effect. It shows that the photoluminescence of CoTe₂ QDs is wavelength dependent. CoTe₂ QDs has the photoluminescence characteristic of multicolor, different excitation light wavelength can emit different colors of light. The fluorescence quantum yield of QDs is 62.6%. The excellent optical characteristics of CoTe₂ QDs, especially its absorption and luminescence characteristics in the infrared band, shows that it has important potential application value in infrared detection, laser protective coating, fluorescence imaging, multicolor luminescence and nano-photonic devices, and is expected to become a new type of infrared detection material.