In order to investigate the effect of manufacturing process on the Degree of binder Activity (DoA) of hot recycled asphalt mixture with regard to the Brazil-nut effect, the manufacturing process parameters such as mixing time, preheating temperature of virgin aggregates, reclaimed asphalt pavement (RAP) size and the adding orders of aggregates with different sizes into the laboratory mixing pot were selected as analysis variables. Without the addition of recycling agent, the mixtures produced from the RAP and the virgin aggregates with large particle size difference were directly mechanically mixed and screened, then the asphalt extraction test were conducted for the screened mixtures, and the binder content of each mixture in terms of different manufacturing process are determined. The results showed that when manufacturing hot - recycled asphalt mixture, the mixing time, preheating temperature of virgin aggregates and particle size of RAP indicated positively correlation with the DoA. Compared with the fine RAP, the DoA of hot recycled asphalt mixture prepared from middle RAP increased by 30% to 60%. The Brazil-nut effect further explained that the RAP with fine particle showed more distribution at the bottom of the mixing pot during the mixing process, and it reduced the contact and collision probability with the virgin aggregate with large particle size in the upper layer , which resulted in the decrease in the amount of binder transfer. This effect can be weakened by prolonging the mixing time, but this reduction is limited.