The invention discloses a preparation method of a concrete surface skeleton exposing agent for a prefabricated part, and the preparation method comprises the following steps: (1) preparation of a polymer/phyllosilicate composite colloidal solution, namely under high-speed dispersion, uniformly dispersing phyllosilicate clay X1 and a water-soluble high-molecular polymer in water; (2) preparation ofan organic-inorganic composite retarding liquid, namely under high-speed dispersion, adding an organic-inorganic composite retarder composition into the polymer/layered silicate composite colloidal solution, and dispersing until no precipitate exists in a homogeneous phase; and (3) skeleton exposing agent forming, namely under the action of high-speed dispersion, sequentially adding a functionalauxiliary agent, a pigment, a filler and a slow-release long-acting preservative into the organic-inorganic composite retarding liquid, and uniformly mixing and dispersing. The concrete surface skeleton exposing agent for the prefabricated part has the multiple advantages of ecological environmental protection, efficient retarding, durability, stability, easiness in facade construction and the like, industrial byproduct gypsum is used as a main retarding component, and secondary utilization of byproducts is realized.