Magnesium hydroxide (MH) whiskers were modified via in situ polymerization of n-butyl acrylate and maleic anhydride.Sodium dodecyl sulfonate was used as emulsifier.The modifying effect was evaluated by using contact angle and activation index.The thermal stability,functional groups,structure,morphology,phase composition and surface element valence of MH whiskers were characterized by thermogravimetry-differential scanning calorimetry (TG-DSC),Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD),scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).Results reveal that the contact angle and activation index of modified MH whiskers are 105° and 76.5％,the thermal stability shows little change,and the decomposition temperature ranges between 38 and 419 ℃.The copolymer of n-butyl acrylate and maleic anhydride absorbed on the surface of MH whiskers leads to the increased diameter and makes the surface of whiskers be rougher.Furthermore,the absorption of element C on the surface of MH whiskers increases,and the diffraction intensity of C ls spectra increases;thus,the compatibility of whiskers in the organic phase can be improved significantly.Lastly,the surface molecular model of MH whiskers modified via in situ copolymerization of n-butyl acrylate and maleic anhydride is established.