Octyl Alginate Derivative (OAD), prepared by bimolecular nucleophilic substitution reaction (SN2) with 1-Bromooctane as a hydrophobic modifier, was characterized by means of Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR) to confirm its structure. Meanwhile, the performance of OAD was characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), fluorescence spectrum (FM), surface tension (SFT), transmission electron microscope (TEM), laser particle size and zeta potential analyzers. The results of FTIR and 1H NMR showed that, the octyl group was suc-cessfully grafted onto the alginate backbone. It can be seen from the TGA and XRD that, due to the grafting octyl side chains, the intramolecular hydrogen bond of OAD was broken, thus resulting in the de-crease of its thermal stability, the increase of its weight loss rate in TGA study and the change of its micro-crystalline structure. From the fluorescence measurement, with the increase of OAD concentration, the ra-tio of the first electron vibration peak to the third electron vibration peak fluorescence intensity (I1/I3) that was related to the micro-environmental polarity surrounding pyrene molecules gradually decreased, indi-cating the reduction of the micro-environmental polarity. It can be deduced from I1/I3 value that, as a re-sult of the grafting of octyl side chains, the critical aggregation concentration (CAC) of sodium alginate (SA) decreased from 1.09 g/L to 0.34 g/L. Meanwhile, the SFT gradually decreased as the concentration increased. Both of the FM and SFT results revealed that OAD had good amphipathicity, though they ob-tained the different CAC. From the TEM, it intuitively displayed that OAD formed micelle-like self-aggregates, which appeared spherical structure. Furthermore, compared with SA, the hydrodynamic particle size (dH) of OAD decreased from 255 nm to 193.2 nm. Besides, its zeta potential also decreases from -36.4 mV to -39.3 mV. These results showed that OAD possessed certain colloidal interface activity. The drug-loaded micro-/nano-capsules were prepared by the use of OAD micelles to load ibuprofen, which have certain sustained-release property, Moreover, the release profile was fitted well with the Non-Fickian diffusion model.