Polypropylene random copolymer and preparation method thereof

The invention provides a polypropylene random copolymer and a preparation method thereof. The preparation method of the polypropylene random copolymer comprises the following steps: 1) adding a prepolymerization catalyst, a cocatalyst and a modifier into a first gas phase reactor, introducing propylene, ethylene and hydrogen into the first gas phase reactor, and carrying out a first polymerizationreaction to obtain a first polymerization reaction mixture; 2) separating a gas phase in the first polymerization reaction mixture to obtain a solid first polymerization reaction mixture; and 3) adding the solid first polymerization reaction mixture into a second gas phase reactor, introducing propylene, ethylene and hydrogen into the second gas phase reactor, and carrying out a second polymerization reaction to obtain the polypropylene random copolymer, wherein the prepolymerization catalyst is a titanium group catalyst, and the activity of the titanium group catalyst is 13000-30000 g/g. Thepreparation method can be