With MnO2 as microwave absorbent, double perovskite Sr2FeMoO6 powder was synthesized by microwave processing using SrCO3, Fe2O3 and MoO3 as starting materials. XRD patterns reveal that the as-synthesized product is Sr2FeMoO6 with tetragonal crystal structure and I4/mmm space group, and the unit cell parameter is a =0.5571 nm as well as c = 0.7872 nm. The grain size of the sample is about 20 nm, calculated by the Scherrer formula using the diffraction data. Magnetism testing results show that the sample is ferromagnet, the transition temperature is higher than room temperature and the saturation magnetization is 17.949 (A·m2)/kg under 1 T at room temperature. Electrical performance testing results show that the sample exhibit typical semiconductor behavior and the conductive mechanism can be described by adiabatic small polaron model. The room temperature magnetoresistance of the sample under 1 T field is up to –15.63%