Abstract: The present invention discloses a method for preparing high-melt-strength polylactide resin by two-step reaction, which comprises the following steps: mixing polylactide resin and GMA to obtain a premix; mixing multifunctional reactive monomer, a peroxide initiator and organic solvent to obtain a monomer mixture; and adding the premix and the monomer mixture into a screw extruder in sections, after melting, blending, extruding, cooling, pelletizing and drying to obtain a high melt strength polylactide resin. The method of the present invention has a simple production process, can be adapted to large-scale industrial production, the graft modification reaction is rapid and controllable, and the obtained product is safe without residue and high in purity. The high-melt-strength polylactide resin has a low melt flow index, high complex viscosity and storage modulus, and is a green polymer material with wide application prospects.