The invention provides a full-shape casting coating and a preparation method thereof, relating to the field of casting. The full-shape casting coating includes the following raw materials in parts by weight: quartz powder, olivine powder, corundum powder, sodium bentonite, lignin sulfonic acid, and dextrin powder , sodium carboxymethyl cellulose, sodium benzoate, hollow glass microspheres, aluminum sulfate, polyvinyl alcohol, silica sol, iron oxide powder, n-octanol, graphite powder, zircon powder, attapulgite, water reducing agent and water The preparation method comprises the following steps: (1) weighing raw materials, (2) preparing each mixed solution in turn, and (3) adding to a reaction kettle and stirring in turn. The invention solves the problem that the existing solid casting coatings generally have strong wear resistance, high adhesion, excellent air permeability and quick drying under high temperature and low temperature environments, which makes them unable to meet the production requirements of large castings. question.