The invention belongs to the technical field of oilfield development, and in particular relates to a cation-type anti-swelling clay stabilizer containing N-heterocyclic quaternary ammonium salt and a synthesis method thereof. The clay stabilizer is generated by performing reaction between anhydride naphthalene and dodecanol to generate dodecyl anhydride naphthalene half-ester, performing solution polymerization reaction with 2-(dimethylamino)chloromethane hydrochloride to generate an intermediate, and finally performing reaction with 2-bromomethylpyridine, wherein the molar ratio of the anhydride naphthalene to the dodecanol to the 2-(dimethylamino)chloromethane hydrochloride to the 2-bromomethylpyridine is 1:1-1.6:1.1-1.5:0.8-1.7, preferably 1:1.1:1.2:1.5. The clay stabilizer is characterized by wide source of raw materials, simple synthesis process, small usage and high reservoir adaptability. The clay stabilizer is good in temperature resistance and salt resistance, the temperature of 220 DEG C can be resisted, the degree of mineralization of 220000mg/L can be resisted, and the compatibility is excellent. The clay stabilizer can be strongly adhered to the surface of clay, is not prone to decomposition, and is long in duration and high in anti-swelling rate which exceeds 98 percent.