The multilayer films of the double-barrier magnetic tunneling junctions (DBMTJs) were deposited by magnetron sputtering. The AlOx insulator was forme d by plasma oxidizing aluminium. The photolithographic pattering procedure combin ed with Ar ion milling was used to microfabricate the DBMTJs with an ellipse of 　π×３×６μm2. Magnetic transport properties of DBMTJs were invest igate d. The junctions show a resistance-area product about 136 kΩ·μm2 and 175 kΩ·μm2, a high tunneling magnetoresistance of 27% and 422% at 3 00 K and 42 K, respectively. A tunneling magnetoresistance oscillation phenome non with respect to the bias voltage was first observed in this experiment. We d esigned a few kind of spin transistors based on the spin-dependent resonant tunn eling effect of the DBMTJs.