Abstract: The whey protein isolate(WPI)and gum arabic(GA)complex were thermally treated in order to prepare stable nanoparticles and improve its stability. The intromolecular soluble complex of WPI/GA was treated by heating,which enables WPI,the molecular electrostatically combined with GA,aggregate and form stable nanoparticles by interwinding with the molecular chains of GA. As shown in the results,the stable and homogenous nanoparticles could be formed through heating on 1% WPI/GA complex at 85℃ for 15 mins,bringing out higher stability of pH. A stable oil-in-water emulsion(containing 20% MCT)could be stabilized with the nanoparticles of 1% WPI/GA complex. Conclusion:the WPI/GA intramolecular complex was heat-treated to entrap the protein during the aggregation process with GA to form stable WPI/GA nanocomposite particles and improve the pH sensitivity of the WPI/GA complexes,which showed good emulsifying activity. It provides a good application prospect as a functional factor of nanocarriers.