As one of carbon nanomaterials, carbon dots have attracted widespread attention due to their ultra-small size, abundant surface functional groups, good chemical stability, and superior optoelectronic properties. In this review, the structures, classifications, characteristics, and preparation methods of carbon dots were introduced. Recent research studies on carbon dots as various components or additives in dye-sensitized solar cells were represented. The challenges of controllable synthesis, structure-property relationship, and performance optimization of carbon dots were analyzed. In addition, the development directions of large-scale controllable preparation for carbon dots and their application in dye-sensitized solar cells were proposed.