Abstract: Natural plant fibers have unique structure and properties, and there are still many problems in compounding with resin matrix. Modification of natural plant fibers has important effect on improving their reactivity, interfacial compatibility with matrix resins and comprehensive properties of composites. Based on the analysis of the composition, structure and performance of natural plant fiber raw materials, some natural fiber pretreatment methods, such as steam-explosion pretreatment, thermal pretreatment, high energy radiation pretreatment, alkali pretreatment, peroxide pretreatment and combined pretreatment, were introduced, as well as some surface modification methods such as esterification modification, graft copolymerization and coupling agent modification. The research progress of natural fiber modification methods in composites and the effects of natural fiber modification on the properties of composites were summarized in order to provide ideas and references for the research of natural fibers reinforced composites.