Mechanochemistry as an energy-saving and highly efficient synthetic method emerges great potential in various chemical syntheses. The multi-phase compatibilizer polypropylene (PP) grafted with maleic anhydride (MAH) and styrene (St) (PP-g-(MAH-co-St)) was successfully obtained by mechanochemical method without any solvent within minutes. The PP-g-(MAH-co-St) with G(MAH) = 0.24-1.40 % were made by mechanochemistry successfully. The impact of monomers concentration, initiator concentrations, particle size of PP, ball-milling time and ball-milling speed on the grafting proportion of MAH onto PP (G(MAH)) was also investigated. The optimum conditions for PP-g-(MAH-co-St) (G(MAH) = 1.40 %) by ball milling were particle size of PP, 0.150-0.250 (mm); MAH/PP ratio, 6 % (m/m); St/PP ratio, 6 % (m/m); DCP/PP ratio, 0.3 % (m/m) at 400 r/min in 30 min. Infrared (IR) spectra and H-1 NMR spectra confirmed the incorporation of MAH and St onto the PP backbone, which also indicated ball milling was an efficient and effective way for the graft of PP-g-(MAH-co-St). [GRAPHICS] .