The invention relates to the field of research, development and application of a novel MXene-based photoelectric detector, in particular to a method for uniformly depositing a thin film based on a liquid-phase MXene material, high-precision patterning and preparing a photoelectric device on a large scale. The method comprises the following steps: spin-coating an MXene material suspension through a spin coater, and preparing a uniform MXene material film on a silicon wafer; and realizing the high-precision patterning of the MXene material thin film by adopting a photoetching-dry etching process. The MXene-based photoelectric detector is composed of a silicon substrate, an electrode, a semiconductor layer, a transparent conductive film layer and the like, the electrode, the semiconductor layer, the transparent conductive film layer and the like are arranged on the silicon substrate, the semiconductor layer is made of n-type silicon formed by doping, the transparent conductive film layer is made of MXene materials, and the electrode is formed by compounding a Ti layer and an Au layer. According to the invention, the patterning of the large-area MXene material film is realized by using a photoetching-dry etching process, so that the high-resolution MXene-based photoelectric detector is constructed, and the MXene-based photoelectric detector has good photoelectric performance and long cycle life.