The invention provides a gasoline engine lubricating oil composition and a preparation method thereof. The gasoline engine lubricating oil composition comprises an anti-oxidation and anti-abrasion agent, high molecular succinimide, salicylate, alkylated diphenylamine, thiocarbamate, an organic molybdenum friction improver, barium sulfonate and lubricating oil base oil. A preparation method of theanti-oxidation and anti-abrasion agent comprises the following steps that dithiophosphorus acid reacts with peroxide, then saponification reaction is carried out with a zinc-containing compound, and an oil phase product is collected. The gasoline engine lubricating oil composition has excellent anti-oxidation and anti-abrasion performance, antifriction performance and dispersion performance, can meet the requirements of high-grade gasoline engine lubricating oil, and prolongs the service life of the oil product.