A method of using adsorption and assemblage-mingle to immobilize the mixed bacteria of purpIe nonsulfur photosynthetic bacteria is used to treat dyeing wastewater and phenolwastewater. The PSB is easy to be adsorbed on rough and porous carriers with high adsorption a-bility under light and anaerobic conditions. In addition, it is abIe to resist some erosion of currentvelocity. After having been detoxified and activated, the immobilized cells of assemblage-mingleare improved for their ferment activity, e. g., the activity of dehydrogenase is 1.0-1.5 timeshigher than that of natural cells and the velocity of decolourization is 30% faster than that of nat-ural cells. The result shows that the method to treat wastewater by PSB is a feasible way to re-duce bacteria losses and to improve activity of ferment.