Under microwave irradiation, the nanocomposite of Ag/TiO2 was prepared by a sol-gel method combined with temperature-programmed treatment in the presence of the triblock copolymer surfactant EO20PO70EO20 (P123). The phase composition, structure and morphology of the nanocomposite Ag/TiO2 were characterized by XRD, XPS, TEM, N2 adsorption-desorption tests and SEM-EDS. The results show that the silver species in the nanocomposite Ag/TiO2 by microwave irradiation is metallic Ag0. The phase of Ag/TiO2 with 5 min microwave irradiation is the best, whose surface area is 100.64 m2·g-1, and the average diameter is ca. 6.9 nm. Compared with the composite without microwave irradiation, the composite with microwave irradiation has small size, good structure and orderly distribution of particles. The photocatalytic activities of the as-prepared materials were studied by the UV irradiation photodegradation of methyl orange. The results show that Ag/TiO2 obtains the highest catalytic activity, when its microwave power is 200 W, and microwave irradiation time is 5 min. Moreover, it is still able to degrade 80% after three cycles.