In order to calculate the void(ε) of two kinds of aggregates with arbitrary mixing ratio, the functional relations between ε and fine material mass fraction(Pf) were divided into three sections:filling, transition and replacement. The mixing mechanism was quantified into four kinds:filling, interference, replacing and wall effect. The interference term was added to the volume equation of asphalt mixture CAVF design to describe the filling section and transition section. The replacing effect and wall effect was used to describe the replacement section. An example was taken to test the model and analyze the model parameters. The results show that the essence of interference is that coarse aggregate is replaced by the fine aggregate, and the fine aggregate mass is responsible for the interference and filling is distributed according to constant k, and its common intervals is[058, 064]. The wall effect can be interpreted as the replacement of fine aggregate by combined coarse aggregate, and the mass distribution constant of coarse aggregate with wall effect and replacing is w. The larger the k and w, the more significant the filling and replacing effect, and the larger the slope of ε Pf curve. The model predictions are basically consistent with the measured values, and the research results can enrich the theory of mineral aggregate gradation.