The effects of different modifiers such as benzoic acid(BA),stearic acid(SA) and toluene-2,4-diisocyanate(TDI) on the properties of polypropylene/wood flour composite were studied.The results show that the surface polarity of the wood flour and interfacial tension between wood flour and polypropylene are decreased but the compatibility is improved after wood flour being treated by these modifiers.The measurements of mechanical properties and melt flow rate of the modified composites also show that all of these modifiers can improve tensile strength,impact strength and melt flow rate of the composites,but have little effect on the flexural strength.In general,the comprehensive properties of the composites reach the best value after wood flour being treated sequentially by TDI and SA.SEM photos show the interface between wood flour and polypropylene gets blurred after wood flour being treated in the cross sectional morphologies of composites.