The invention belongs to the field of polyolefin resin materials, and particularly relates to a polypropylene composition and a preparation method thereof. The polypropylene composition comprises the following raw materials in part by weight: 100 parts of a polypropylene resin random copolymer, 0.05-0.3 part of an anti-oxidant, 0.06-0.4 part of a nucleating agent A, 0.04-0.3 part of a nucleating agent B, 0.02-0.1 part of an acid acceptor and 0.02-0.08 part of an antistatic agent. According to the preparation method, a high-fluidity polypropylene random copolymer, which is obtained according to the hydrogen regulation method, is used as the basis resin; additives, such as the anti-oxidant, the acid acceptor, the antistatic agent, the nucleating agent A and the nucleating agent B, are added into the basis resin; after the basis resin and the additives are uniformly mixed by a high-speed stirring machine, the high-fluidity high-transparency polypropylene composition is obtained through double-screw extrusion pelletizing. The polypropylene composition is excellent in comprehensive performance, high in transparency and fluidity, resistant to warpage, and superior to a product of the degradation method in the aspects of appearance, color, lustre and smell. Therefore, the polypropylene composition can be applied to a large-scale transparent product and a complicated thin-wall product, and the warpage phenomenon during the production can be effectively avoided.