Multifunctional　nanoparticles　as　theranostic　tools　hold　great　potential　for　its　unique　and　efficient　way　to　visualize　the　process　of　disease　treatment.　However,　the　toxicity　of　conventional　fluorescent　labels　and　difficulty　of　functionalization　limit　their　widespread　use.　Recently,　a　number　of　amino-rich　polymers　have　demonstrated　high　luminescent　fluorescence　but　rarely　showed　potential　for　in　vivo　imaging　due　to　their　blue　fluorescence.　Here,　a　general　route　has　been　found　to　construct　polymer-based　multifunctional　nanoparticles　for　combined　imaging　and　drug　delivering.　The　weak　fluorescent　polyethyleneimine　(PEI)　has　been　conjugated　with　hydrophobic　polylactide　as　the　amphiphilic　PEI　for　construction　of　nanoparticles　which　showed　bright　and　multicolor　fluorescence　with　high　drug　loading　capacity.　The　paclitaxel-loaded　nanoparticles　showed　significant　therapy　effect　in　contrast　to　the　free　paclitaxel.　Meanwhile,　fluorescence　imaging　of　the　nanoparticles　showed　accumulation　around　tumor.　These　results　demonstrate　a　new　type　of　polymer-based　multifunctional　nanoparticles　for　imaging-guided　drug　delivery.