The invention discloses a quaternary thioarsenate compound semiconductor material and a preparation method and application thereof. The preparation method includes: using alkaline-earth metal hydroxide, silver, a binary solid solution As2S3 and a simple substance S as the raw materials and hydrazine hydrate as the solvent to perform reaction in a drying oven of 160 DEG C for 4-7 days to obtain thequaternary chalcogenide semiconductor material with the chemical formula being SrAg4As2S6.H2O. The preparation method has the advantages that the method is simple in operation, simple in raw materials, low in raw material cost, mild in reaction condition, low in synthesizing temperature and the like; the quaternary chalcogenide semiconductor material prepared by the method is high in chemical purity and can be used for preparing optical semiconductor devices or solar cell transition layers, and the yield of the quaternary chalcogenide semiconductor material can reach 50%.