The invention discloses a starch-containing thickening agent copolymerization association compound and a preparation method thereof. The copolymerization association compound contains a structural unit A, a structural unit B, a structural unit C and a structural unit D, the structural unit A is N,N-dimethylacrylamide, the structural unit B is an amphoteric monomer methacryloyloxyethyl-N,N-dimethylpropanesulfonate (DMAPS), the structural unit C is an ion association body of the structural unit B and cationic polyamine, and the structural unit D is starch; and based on the total amount of the copolymerization association compound, the content of the N,N-dimethylacrylamide is 6-45% by weight, the total content of the amphoteric monomer methacryloyloxyethyl-N,N-dimethylpropanesulfonate is 5-35% by weight, the content of the cationic polyamine is 2-30% by weight, and the content of the starch is 5-35% by weight. Temperature resistance of the thickening agent prepared by the method can reach 150 DEG C, anti-NaCl concentration is saturated, and anti-CaCl2 concentration reaches 20%; and meanwhile, excellent shale inhibition performance and filtrate loss controllability are furthermore achieved.