Anti clogging performance of porous asphalt concrete（PAC） were researched by designed clogging test and water permeation test, it was analyzed that the air voids clogging of PAC was influenced by air voids, nominal maximum aggregate size, graduation and blocking particles size, variation trend was researched on the permeability of PAC after air voids clogging. The results show that there have big differences of anti clogging performance with different PAC material composition; PACs anti clogging performance can be raised by increasing air voids, nominal maximum aggregate size and using coarse gradation with similar air voids; the location of blocking occurred are concentrated on the top 30mm of PAC 13 specimen, fine particles with size of about 1.182.36mm are the key particle size which caused the clogging in the surface of PAC 13 specimen, fine particles with size of about 0.150.30mm are the key particle size which caused the clogging in the top and middle part of PAC 13 specimen.