The La0.7Sr0.3MnO3/Nb-1wt%-doped SrTiO3 p-n junction fabricated by the magnetron sputtering technique exhibits excellent rectifying characteristics over the temperature range from 40 to 320 K, nearly independent of the temperature. The modulated electromagnetic property of La0.7Sr0.3MnO3 is also achieved by the built-in electric field near the interface of junction. The diffusion potential decreases almost linearly with increasing the temperatures. It can be understood by considering a picture that the depletion layer in p-n junction becomes thinner and thinner with the increase of temperature due to the thermal diffusion effect. In addition, this phenomenon is also attributed to the variation of the electronic structure of LSMO with temperature increasing. The junction resistance decreases sharply when the applied forward current increases from 1 mA to 50 mA while the insulator-metal transition temperature TP increases from around 200 K to 250 K due to the strength enhancement of the ferromagnetic double-exchange interaction