The material composition and microstructure have a comprehensive influence on geological engineering properties of dredger fill． The porosity of the dredger fill is an important characteristic of microscopic structure． Taken dredger fill from Binhai New Area in Tianjin as research object，the distribution trend of pore is obtained by granularmetric analysis，mineral composition analysis and mercury intrusion method． By discussing the variation regulation of dredger fill in two different kinds of processing methods，certain theoretical basis is provided for evaluating the engineering geological properties of dredger fill． It can be concluded from the test results that after drainage treatment，the porosity decreased and the structure unit changed from the relatively loose state to aggregate state． In certain depth range，the consolidation effect of dredger fill with drainage treatment is better than that without drainage treatment．