A novel signal-on fluorescence biosensor for detection of adenosine triphosphate (ATP) based on the target induced recombination of split aptamer fragments and click chemistry is proposed. The CuS NPs modified on the streptavidin magnesphere paramagnetic particles (PMPs) can be destroyed by acid to form Cu(II). In the presence of sodium ascorbate, Cu(II) can be reduced to Cu(I) which in turn catalyzes the reaction between a weak-fluorescent 3-azido-7-hydroxycoumarin and propargyl alcohol to form strongly fluorescent 1,2,3-triazole compounds. The proposed sensor has been applied to the detection of ATP in human serum samples with satisfactory results.