Drainage asphalt mixture mainly relies on internal connected voids to discharge surface water accumulation, but currently our design still considers void fraction rather than connected void fraction. To gain a more accurate understanding of the relationship between void fraction, connected void fraction, and drainage capacity, and to investigate the influence of sieve pass rate on connected void fraction, PAC-10 drainage asphalt mixture with different sieve pass rates was formed through indoor experiments to detect their void fraction, connected void fraction, and permeability coefficient. The results show that the volumetric method is more accurate in measuring porosity and connected porosity compared to the vacuum plastic sealing method, and connected porosity can better reflect the drainage capacity of drainage asphalt mixtures; By using linear fitting method, it is found that there is a linear relationship between porosity and connected porosity when the porosity is greater than 20%. When the porosity is less than 20%, the difference between porosity and connected porosity begins to increase; By using the forward method to screen variables and conducting regression analysis on experimental data, it was found that there is a linear relationship between the connected porosity and the pass rate of the 2.36 mm sieve. The smaller the pass rate of the 2.36 mm sieve, the greater the connected porosity; The connectivity porosity is only affected by the 4.75 mm pass rate, second only to the 2.36 mm pass rate. The closer the difference in pass rates between 4.75 mm and 2.36 mm, the greater the connectivity porosity.