Natural dye obtained from green algae is used for dyeing wool fibers which are used in handloom carpets. Environmentally friendly pretreatment with chitosan and tannic acid were used for enhancing the dyeability of wool fibers. Factors affecting the dyeing properties such as dye concentration and time of dyeing with microwave were studied. Color strength was measured for dyed wool fibers.The results indicate that, wool fibers pretreated with chitosan and tannic acid leads to high color strength than the untreated fibers. The antimicrobial activity of dyed wool fibers pretreated with chitosan and tannic acid were studied. Some forms of bacterium and Fungi were tested, and therefore the results indicated that the pretreated samples exhibit higher growth reduction % than the untreated samples. Microwaves heating is eco-friendly, saving time and energy.