Abstract: Oxide molecular beam epitaxy technique has been rapidly developed in the recent years.Oxide films and heterostrutures can be made with the precision of single atomic layer,which has helped facilitate the research of high temperature superconductivity,two dimensional electron gas,and oxide-based electronics and spintronics.Taking La1-xSrxMnO3 thin film as an example,we introduce the oxide molecular beam epitaxy and basic characterizations for a perovskite thin film.Moreover, we show that by combining oxide molecular beam epitaxy and angle resolved photoemission spectroscopy,in-situ electronic structure measurements become feasible for thin films.The measured electronic structure of La1-xSrxMnO3 thin film shows fairly good agreement with the band structure calculations,while previously the electronic structure of such uncleavable cubic-structured materials usually could not be obtained with photoemission spectroscopy.