Abstract: Used citric acid as a modifier for surface treatment of talc，the modified talc and polypropylene（PP）were prepared by melt blending and obtained a series of PP/talc composites. With infrared absorption spectrum，scanning electron microscopy（SEM），impact properties test，tensile properties test and other experimental methods，researched the modified talc influence of the internal microstructure，mechanical properties and flow properties to the composites. The results showed that：the talcum powder after citric acid modifing can obviously improve the compatibilitys between talcum powder particle and PP，promote the talcum evenly dispersed in PP matrix，and improved processing flow properties，impact properties，tensile properties and other mechanical properties，toughened and reinforced PP.

Key words: polypropylene, talc, citric acid, mechanical property, flowing property