Abstract: β- carotene( β- CE) has various biological activities,but it is unstable and easily degradation.β- carotene self- assembles in casein( CN) and form nanoparticle complex,with plays an important role in protecting β-carotene.Thereby,β- carotene / CN nanoparticle complex can enhances the utilization value of β- carotene in the food industry.The paper was based on the formation of β- CE / CN nanoparticle complex,and the influence factors,such as formation,the particle size distribution and bioavailability of β- CE were investigated. The results showed that temperature and β- CE / CN mass ratio had great impact on its formation,β- CE re- assembled in CN can improve water solubility of β- CE.After digestion experiment in vitro,β- CE was hydrolyzed by trypsin and pepsin,the hydrolysis degree of casein was increased with the increase of hydrolysis time.Therefore,β- CE easily released from β- CE / CN nanoparticle complex and its bioavailability was enhanced.