Because of the novel electron transport and spin-magnetic characteristics, the potential applications of rare-earth alloy manganites have been expected a lot. In recent 5 years, a new type of p-n junctions has been fabricated bY growing the p-type manganite thin film on the n-type SrTiO3 substrate. In this paper, we would like to introduce the research on this novel device and forecast the prospect of the manganite p-n junction.