[Purposes] This paper aims to study the difference in water permeability between porous asphalt mixture PAM-10 and open-graded asphalt mixture with water drainage function OGFC-10, so as to select asphalt mixture types for drainage pavement. [Methods] PAM-10 asphalt mixture specimens with void rates of 12.5%, 14.0%, 15.5%, 17.0% and the OGFC-10 asphalt mixture specimen with the void rate of 22.0% were subjected to the connected void rate test, vertical permeability coefficient test, scouring resistance test, and clogging resistance test were conducted, and their void interior characteristics were analyzed by computed tomography (CT). The water permeability of the two kinds of asphalt mixtures was compared. [Findings] The void structure of PAM-10 makes it easier to form the connected voids than OGFC-10. The vertical permeability coefficient of PAM-10 with the void rate of 17.0% is similar to that of OGFC-10 with the void rate of 22.0%. The effect of dynamic water scouring on OGFC-10 is greater than that on PAM-10. OGFC-10 has poorer clogging resistance than PAM-10. [Conclusions] The vertical permeability, scouring resistance, and clogging resistance of PAM-10 are all better than those of OGFC-10.