The invention relates to a cyanine dye having an azulene structure, which has a molecular structure represented by a general formula below. The method for preparing the cyanine dye comprises the following steps: taking 1,3-dimethyl acyl azulene derivant and 1-alkyl-2,3,3-trimethyl indole salt as raw materials; performing condensation reaction in an inert solvent under the action of a condensing agent; and performing purification to obtain an objective product. The cyanine dye having the azulene structure has high purity, high yield, easy purification, large molar extinction coefficient and high solubility in organic solvents, is suitable for sensitive materials, CD recording media, infrared laser dyes and optical nonlinear materials, and is used for the fields of biomedicine and the like.