The invention discloses a paint thickener for printing and a preparation method thereof. The preparation method comprises the following steps: using unsaturated and acidic monomers, crosslinking agent, unsaturated compound and functional monomers to perform inverse emulsion polymerization in hydrocarbon solvent under the action of initiator and oil-soluble emulsifier and performing inverse emulsion, wherein unsaturated and acidic monomers are neutralized before the polymerization. The paint thickener for printing of the invention has excellent thickening ability and electrolyte tolerance performance, high colour yield and soft hand feeling.