密近双星是两子星距离较近，一子星对另一子星演化产生影响的双星系统，其形成和演化一直是天体物理学中未解决的难题。人们对这类双星起源的一个猜想是这类双星是通过伴星天体转移角动量形成的，伴星天体对密近双星的形成和演化起着重要的作用。由于Algol型双星是所有密近双星中观测历史最长且食很深很尖锐的一类双星，是寻找密近双星伴星天体最重要的场所，本项目选取这类天体为研究对象，立足于使用国内中小口径望远镜，对挑选出的Algol型双星系统进行监测，获取其掩食光变曲线，利用光时效应原理搜寻其周围的伴星天体并获得其物理参量。项目的实施和完成不仅能对密近双星系统的起源和演化提供重要的信息，更好地理解双星的演化链条和各种可能的结局，增加人类对宇宙中恒星系统多样性的认识，同时为更多特殊共双星伴星天体的发现提供观测证据。

Close binary stars mean that the two components of these systems are so close that one component have an interaction on the evolution of the other one. The formation and evolution mechanism of close binary stars have been an unsolved problem in astrophysics. One speculation is these binary stars formed through angular momentum transfer of companion stars which play an important role in the formation and evolution of close binary stars. In all close binary stars, Algol-type binaries have the longest observational history, with deep and sharp eclipse shape, therefore, it is the most important places for searching companion stars. We choose Algol-type binaries as research objects, obtain eclipse light curves after secular monitoring by taking advantage of small and medium telescopes. Meanwhile, searching for companion objects around Algol-type binaries and calculating the physical parameters of them by using the light time effect theory. Implementation and completion of the project will not only provide important information on the origin and evolution of close binary systems, but also present a better comprehending on the evolution chain and variety of possible evolution ending of close binaries. Furthermore, it will improve our understanding on the diversity of stellar systems and provide observation evidence for more special circum-binary companion objects.