Benefit　from　the　additional　correction　of　the　output　signal　in　dual-mode　detection,　traditional　dual　signal　readout　strategies　are　performed　by　constructing　the　ratiometric　fluorescent　probe　through　excitation　energy　transfer　(EET)　or　fluorescence　resonance　energy　transfer　(FRET).　To　avoid　the　complicated　modification　process　and　obtain　the　results　rapidly,　a　simple　dual-mode　sensing　strategy　based　on　the　electronic　effects　of　p-nitrophenol　(PNP)　is　described　to　monitor　the　activities　of　alkaline　phosphatase　(ALP).　In　the　sensing　platform,　p-nitrophenylphosphate　was　used　as　a　substrate　to　produce　the　PNP　using　ALP　as　the　catalyst.　Due　to　the　PNP　possesses　negative　effect　of　induction　and　conjugation,　photoinduced　electron　transfer　and　hyperchromic　effect　have　been　achieved　between　PNP　and　polyethyleneimine-protected　copper　nanoclusters　(PEI-Cu　NCs),　which　caused　the　changes　of　the　fluorescence　intensity　and　UV–visible　absorption.　The　dual-mode　signal　sensing　system　showed　the　satisfactory　linear　results　of　ALP　from　1　to　100　U/L　for　fluorescent　sensing　strategy　and　1–70　U/L　for　the　absorption　method　with　a　competitive　LOD　of　0.27　and　0.87　U/L　(signal-to-noise　ratio　of　3).　This　strategy　detected　biological　ALP　in　human　serum　and　bio-imaging　of　endogenous　ALP　in　A549　cells　successfully,　which　verifies　a　certain　potential　of　the　strategy　for　the　practical　applications.　©　2020