Aggregation behaviors of two anionic azo polyelectrolytes with different chemical structures were studied in the tetraphydrofuran(THF)／water mixture．The aggregating process was traced by UV-Vis absorption spectroscopy and the aggregates formed were imaged with transmission electron microscopy(TEM)．The pH effect on the aggregation was also investigated．With the increasing of water content in THF／water mixture

the azo chromohpores in the polyelectrolytes aggregate gradually

which results in an obvious blue-shift of the absorption maximum and a decrease of absorption intensity in the UV-Vis spectra．In the solutions with high concentration of azo polyelectrolytes

the aggregates were visualized with TEM to be nano particles with average diameter of about 80 nm．Results shows that the aggregates are much more stable than the related aggragates formed form small azo functionalized amphiphile．In addition

due to the difference in the architecture style of zao chromophores and carboxyl groups

pH of the medium has an opposite effect on the PCAPE and PPAPE aggregates．