The invention discloses a rare earth elements co-doped indium sulfide material as well as a preparation method and application thereof. The indium sulfide material is formed in a way that rare earth elements Yb and Tm are co-doped with indium sulfide. The preparation method comprises the following steps: dissolving an indium source, an ytterbium source, a thulium source and a sulfur source into water, so as to obtain mixed solution; performing a hydrothermal reaction on the obtained mixed solution; and performing washing and vacuum drying, so as to obtain the rare earth elements co-doped indium sulfide material. The rare earth elements co-doped indium sulfide material has the advantages of narrow energy gap, wide spectral response characteristic, and high photogenerated charge separation efficiency; and the preparation method has the advantages of being simple in process, strong in operability and low in production cost, being environment-friendly and pollution-free. When the rare earth elements co-doped indium sulfide material is used for treating heavy metal wastewater or dye wastewater, the indium sulfide material has the advantages of being short in reaction time in a treatmentprocess, high in utilization efficiency of solar energy, high in photocatalytic conversion efficiency, convenient in operation and the like, and therefore, the indium sulfide material can be widely applied to elimination of toxicity and harmless treatment for heavy metals and dyes in the wastewater and has great importance.