Clinically　approved　photodynamic　therapy　(PDT)　has　emerged　as　an　alternative　treatment　for　cancers　and　malignant　diseases;　however,　high　quality　PDT　agents　were　still　in　great　demand.　Herein,　the　van　der　Waals　(vdW)　heterostructure　of　graphitic　carbon　nitride　(g-C3N4,　abbreviated　as　CN　here)　and　metallic　molybdenum　disulfide　(1T-MoS2,　abbreviated　as　MS　here)　was　fabricated,　PEGylated,　and　then　investigated.　By　making　use　of　the　extraordinary　antenna　effect　and　the　ultrafast　electron　transfer　rate　of　metallic　molybdenum　disulfide,　as　well　as　the　efficient　separation　of　photogenerated　electron-hole　pairs　of　the　final　heterojunction,　massive　reactive　oxygen　species　(ROS)　can　be　generated　under　670　nm　laser　irradiation　together　with　the　as-synthesized　gC3N4@1T-MoS2　vdW　nanostructure　(CNMS),　which　should　be　largely　owed　to　the　appealing　photocatalytic　water　splitting　property　of　the　CNMS　structure.　It　was　well　proved　by　the　in　vitro　studies　that　the　intracellularly　produced　ROS　can　result　in　cell　death,　by　the　way　of　inducing　cell　apoptosis　and/or　necrosis　through　mediating　phosphatidylserine　ectropion,　mitochondrial　depolarization,　and　chromosomal　DNA　fragmentation,　as　well　as　up-regulating　the　expression　of　apoptosis-related　proteins　and　unbalancing　intracellular　redox　homeostasis.　In　vivo　exploration　also　gave　out　satisfactory　results　that　the　tumor　growth　could　be　significantly　inhibited　by　the　photodynamic　therapy.　Additionally,　outstanding　biocompatibility　and　biosafety　were　also　guaranteed.　All　these　results　provided　compelling　evidences　for　that　the　CNMS　vdW　heterostructure　is　an　aussichtsreich　nanophotosensitizer,　and　may　provide　some　fresh　ideas　for　the　developing　of　nanomedicine　for　PDT　application.