The　effects　of　graphene　oxide　(GO)　on　the　microstructure　and　resistance　to　chloride　ion　(Cl-)　penetration　of　matrix　containing　0-0.05%　GO　were　investigated　through　isothermal　calorimetry,　thermogravimetric　analysis,　X-ray　diffraction,　mercury　intrusion　porosimetry　and　the　rapid　chloride　penetration　test　method.　A　proper　dosage　of　GO　promoted　the　hydration　process　of　cement,　increased　the　calcium　hydroxide　(Ca(OH)(2))　content,　refined　the　size　of　calcium　hydroxide,　promoted　the　formation　of　high-density　calcium　silicate　hydrate　and　improved　the　pore　size　distribution　of　cement　matrix.　Compared　to　the　group　without　GO,　the　porosity　of　concrete　containing　0.03%　GO　decreased　by　8.56%,　the　largest　pore　diameter　decreased　by　29.05%　and　pores　larger　than　50　nm　were　reduced　by　36.93%.　In　addition,　the　incorporation　of　GO　improved　the　resistance　to　chloride　ion　penetration　of　concrete.　The　charge　passed　through　the　concrete　first　decreased　and　then　increased　with　the　increasing　GO　dosage.　When　the　dosage　of　GO　was　0.03%,　the　charge　passed　through　the　concrete　was　27.71%　lower　than　that　of　the　control　group.　There　was　a　significant　correlation　between　the　permeability　of　chloride　ions　and　pore　structure,　especially　the　proportion　of　pores　larger　than　50　nm　of　concrete.