Ferroelectric (Ba,Sr)TiO3 thin films have excellent ferroelectric/dielectric properties, and promising application prospect in tunable microwave devices and dynamic random access devices. In this article, their research backgrounds, basic structures, preparation methods, various characterizations of thin film properties, and applications are summarized. Furthermore, the several important problems of the current researches of (Ba,Sr)TiO3 thin films are also discussed in great detail based on the acquired research results.