Preparation method of high-melt-strength polyolefine comprising hybrid long branch-chain structure

The invention discloses a preparation method of high-melt-strength polyolefine comprising a hybrid long branch-chain structure, comprising the following steps of: (1) weighting 100 parts by weight of polar monomer grafted polypropylene (a component A) with a grafting rate which is greater than or equal to 0.3 percent by weight, 5-30 parts by weight of polar monomer grafted polyethylene (a component B) with a grafting rate which is greater than or equal to 0.3 percent by weight, 1-10 parts by weight of amine or alcohol compound, 0-0.5 part by weight of antioxidant and 0-0.5 part by weight of light and heat stabilizing agent; (2) diluting the amine or alcohol compound into 20-80 percent by weight of solution by alcohol and/or ketone; (3) adding the component A, the component B, the antioxidant and the heat stabilizing agent into an extruder through a feeding hole, respectively adding the solution obtained in the step (2) and supercritical carbon dioxide from a first side line and a second side line, and melting