By　integrating　imaging　and　drug-delivery　in　a　single　system,　fluorescent　nano-multifunctional　imaging　platforms　can　offer　simultaneous　diagnosis　and　therapy　to　diseases　like　cancer.　However,　the　synthesis　of　such　system　involves　a　tedious,　time-consuming,　and　multi-step　process.　Herein　we　report　a　facile　method　based　on　simple　ultrasonication　to　synthesize　highly　cross-linked,　monodispersed　fluorescent　polyphosphazene　nanoparticles　from　hexachlorocyclotriphosphazene　(HCCP)　and　dichlorofluorescein　(FD).　Various　functional　groups　(folic　acid,　PEG-NH2,　and　methylene　blue)　can　be　＂fastened＂　in　situ　onto　the　poly(cyclotriphosphazene-co-dichlorofluorescein)　(PCTPDF)　nanoparticles　to　expand　its　application　as　nano-multifunctional　platform.　All　the　nanoparticles　were　characterized　spectrophotometrically,　and　morphology　was　established　by　the　images　obtained　from　scanning　electron　microscope　(SEM).　The　synthesized　multifunctional　nanoparticles　exhibited　low　toxicity　and　penetrated　through　the　cytomembranes　of　human　colon　cancer　(HCT　116)　cells.　When　applied　to　in　vivo　tumor　imaging　using　biologically　engineered　mouse　model,　methylene　blue　functionalized　(PCTPDF@MB)　nanoparticles　exhibited　excellent　photodynamic　activity　and　imaging　ability.　Thus,　PCTPDF　nanoplatform　based　on　multi-functional　fluorescent　nanoparticles　might　offer　an　efficient　solution　to　new　age　theranostics.　Apart　from　diagnostics　application,　PCTPDF,　as　a　nanoplatform,　could　also　be　utilized　to　achieve　more　comprehensive　application　in　modern　analytic　chemistry.