Abstract: Coumarin-containing styrene monomer (CS) was designed and synthesized, which could be used together with styrene (St) and maleic anhydride (MA) to synthesize the photosensitive amphiphilic alternating SMA terpolymer poly(styrene/coumarin-containing styrene-alt-maleic anhydride) (P(St/CS-alt-MA)) via free radical copolymerization. Then a new photosensitive amphiphilic comblike terpolymer (P(St/CS-alt-MAA8)) with long alkyl side chains was obtained by the functional amidolysis reaction between succinic anhydride unit and octylamine, and its structure was characterized by gel permeation in chromatography (GPC), Fourier transforminfrared spectroscopy (FTIR), and 1Hnuclear magnetic resonance (1HNMR). It was found that the comblike polymer could aggregate by the photo-dimerization of the coumarin pendants under UV irradiation (>300 nm), and formnanoscale micelles by self-assembly in selective solvent. The micelles could be modified by the ionization of carboxylic acid groups with NaOH. Pyrene loading experiment and dynamic laser scattering (DLS) showed that the micelle diameter and the loading capacity of precrosslinked polymer were bigger than those of non-crosslinked polymer. Micelles reformed after ionization, which made the hydrophobic area denser and the micelle diameter smaller, while the loading capacity also increased.