Prussian　blue　nanoparticles　(PBNPs)　have　attracted　increasing　research　interest　in　immunosensors,　bioimaging,　drug　delivery,　and　application　as　therapeutic　agents　due　to　their　large　internal　pore　volume,　tunable　size,　easy　synthesis　and　surface　modification,　good　thermal　stability,　and　favorable　biocompatibility.　This　review　first　outlines　the　effect　of　tumor　markers　using　PBNPs-based　immunosensors　which　have　a　sandwich-type　architecture　and　competitive-type　structure.　Metal　ion　doped　PBNPs　which　were　used　as　T-1-weight　magnetic　resonance　and　photoacoustic　imaging　agents　to　improve　image　quality　and　surface　modified　PBNPs　which　were　used　as　drug　carriers　to　decrease　side　effects　via　passive　or　active　targeting　to　tumor　sites　are　also　summarized.　Moreover,　the　PBNPs　with　high　photothermal　efficiency　and　excellent　catalase-like　activity　were　promising　for　photothermal　therapy　and　O-2　self-supplied　photodynamic　therapy　of　tumors.　Hence,　PBNPs-based　multimodal　imaging-guided　combinational　tumor　therapies　(such　as　chemo,　photothermal,　and　photodynamic　therapies)　were　finally　reviewed.　This　review　aims　to　inspire　broad　interest　in　the　rational　design　and　application　of　PBNPs　for　detecting　and　treating　tumors　in　clinical　research.