Polypropylene resin preparation method

The present invention relates to a polypropylene resin preparation method, which is characterized in that a sorbitol-phosphate-rosin-carboxylate composite nucleating agent is added to a polypropylene resin, wherein sorbitol, phosphate, rosin and carboxylate are compounded according to a weight percentage ratio of 20-100/0-30/0-25/0-25, and the addition amount of the composite nucleating agent is 0.1-1.0 of the amount of the resin; an aging resistance auxiliary agent comprises a lactones antioxidant, a hindered phenol antioxidant and a nontoxic amine antioxidant according to a mass ratio of 1:0.1-10:0-10, wherein the addition amount of the aging resistance auxiliary agent is 0.1-1.0% of the amount of the resin; and the addition amount of a light stabilizer is 0.1-0.5% of the amount of the resin, melting and uniform mixing are performed in a mixer, and extrusion is performed in an extruder to prepare the polypropylene resin. According to the present invention, the preparation method has characteristics of low c