This invention relates to a method for preparing propylene material with high melt strength. The propylene material is composed of: propylene 100 parts, organic peroxide initiator 0.002-4 parts, multifunctional monomer 0.005-5 parts, branching promoter 0.001-4 parts, and organic clay 0.1-10 parts. The dispersion degree of organic clay is 10-100 nm. The method comprises: uniformly mixing propylene, organic peroxide initiator, multifunctional monomer, branching promoter and organic clay, adding into a twin-screw extruder, melting, extruding and granulating with temperature, rotation speed and feeding rate controlled to obtain gel-free propylene material with high melt strength. During the in-situ intercalation process, organic clay is dispersed in the polymer matrix on nanoscale. Uniformly dispersed organic clay can control the formation of branching structure, and improve the melt strength and mechanical properties of the propylene material. The propylene material is suitable for extrusion foaming and other thermal molding processes.