Abstract: A kind of hyperbranched azopolymers (HPAzoAMAM) with different structures and molecular weights were successfully synthesized via Michael addition polymerization between A₂ and B₂B' monomers. All the structures of HPAzoAMAM and their corresponding molecular weights were analyzed. HPAzoAMAM can self-assemble into aggregates with different morphologies and sizes in aqueous solution confirmed by SEM, TEM and DLS. The photo-isomerization of HPAzoAMAM in DMF and micelle solution were both studied through UV-Vis spectrophotometer. The final results showed that the structure of HPAzoAMAM could be modulated by controlling the molar ratio of the initial A₂ and B₂B' monomers. HPAzoAMAM could self-assemble into large spherical compound micelles (LCMs) with various sizes in aqueous solution because of their different hydrophilicities and molecular weights. With the increasing of the hydrophobicity and molecular weight of HPAzoAMAM, the size of LCMs turned to be larger. The reversible transcis isomerization behavior of HPAzoAMAM in DMF and micelle aqueous solution were studied by UV-Vis irradiation. The results showed that all the absorption peaks of HPAzoAMAM in DMF were at the same positon of 377 nm, while those of the micelle aqueous solutions of HPAzoAMAM-1, HPAzoAMAM-2, HPAzoAMAM-3 were at 376, 367 nm and 372 nm, respectively. Therefore, HPAzoAMAM aggregates were in different π-π stacking styles. Furthermore, in the case of HPAzoAMAM micelle isomerization, the time for reaching stationary state was much longer than that in DMF solution, which was attributed to the highly regular arrangement of azobenzene moieties in aggregates and the restriction of the hyperbranched structures. The feasible combination of azobenzene and hyperbranched polymer provides a promising guidance for the application research of azopolymers.