The　AgNPs@NCN　composite　was　prepared　by　loading　silver　nanoparticles　(AgNPs)　onto　the　surface　of　carbon　nitride　(g-C3N4)　with　nitrogen-vacancy　and　cyanide　defect　and　used　for　the　synergistic　degradation　of　methylene　blue　(MB)　by　the　structural　defect　of　g-C3N4,　the　surface　plasmon　resonance　of　AgNPs　and　Schottky　barrier　formed　between　them.　The　morphology,　structure,　chemical　composition　and　photoelectrochemical　properties　were　characterized　by　SEM,　TEM,　FTIR,　XRD,　XPS,　BET　and　UV-Vis.　The　effects　of　different　loads　of　AgNPs　on　photocatalytic　performance　were　investigated　and　the　results　showed　10%AgNPs@NCN　exhibited　good　photodegradation　performance.　The　maximum　degradation　efficiency　of　MB　by　10%AgNPs@NCN　reached　100%　with　the　rate　constant　of　0.05443　min-1,　which　was　9.15　and　6.89　times　higher　than　those　of　g-C3N4　(0.00595　min-1)　and　NCN　(0.0079　min-1),　respectively.　The　mineralization　degree　of　organic　pollutants　was　evaluated　by　total　organic　carbon　(TOC)　and　the　results　showed　that　the　TOC　removals　of　10%AgNPs@NCN　photocatalytic　reaction　were　77%　and　93%　for　MB　and　wastewater,　respectively.　After　four　cycles　of　photocatalytic　degradation　experiments,　the　degradation　rate　of　MB　was　still　more　than　98.2%　and　there　was　no　significant　change　in　the　characteristic　stretching　of　the　catalyst,　indicating　that　the　prepared　photocatalyst　had　good　stability　and　reusability.